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Korea’s AutoFlex Shaft: Challenging the conventional wisdom of golf



We are creatures of habit, or so I’ve been told. And God knows old habits are hard to break. Just ask my right leg that simply refuses to stop reverse-pivoting, despite my best intentions.

Equally hard to break are pre-conceived notions and superstitions. There are hundreds of them to be sure, but I want to focus on one particular idea in golf that seems to be largely unchallenged for its conventional wisdom: The more flexible the shaft, the less accurate it is.

You may have heard a similar version of the same idea. Stiffer shafts offer straighter shots, faster swingers need stronger shafts, and whippier shafts result in more slice. But a recent find has caused me to challenge this well-established notion—that an ultralight, super flexible shaft (44 grams) is claiming to be not only straighter but longer as well.

My first reaction: “NO WAY”. The shaft would practically be a fishing rod. There’s no way that it would stand up to my normal swing speed of 98~100 mph.

But the kicker was that the makers of this ‘breakthrough’ shaft doubled down on me by claiming that their fishing rod-esque shaft can hold under swing speeds of up to 150mph! That’s up in the territory of world long drive champions-and they are practically inhuman! Now I was scoffing out loud—time to put the money where their mouth was.

(Jung-hwan MOON, member of Korean National long drive team, testing out the new AutoFlex FS505 shaft)

The new shaft is named AUTO FLEX. Sounds a little cheesy, until you realize that Dumina Inc., the South Korean shaft manufacturer, also makes AUTO POWER shafts that have caused a local sensation on the KLPGA and elite amateur circles over the past few years.

Autopower shafts have proven itself to be effective, largely due to a wide range of 50+ shafts offering a much smaller gapping of about 5-10 CPMs between shafts. It allowed golfers to dial into their particular swing speed more effectively. Its use of their proprietary weaving pattern and as-yet-undisclosed material KHT (Korea Hidden Technology!?) also did what it said it would. Smooth feel, mid-high launch, and great accuracy/forgiveness.


Enter AUTO FLEX, the new generation of shafts that Dumina claims will make the game of golf easier and more enjoyable for all golfers. By allowing golfers to swing more easily and smoothly with a much lighter shaft, golfers will not only feel fewer aches and pains but that their scores will improve as well.

Oh, and did I mention that there are only 3 shafts that are supposed to fit all levels of swing speeds from 65 to 150mph?

“NO WAY”, you say? I told you so.

Autoflex SF305 shaft / 38 grams / approx. 170cpm / Ladies / SS 60~80mph
Autoflex SF405 shaft / 44 grams / approx. 180cpm / Men / SS 80~95mph
Autoflex SF505 shaft / 51 grams / approx. 210cpm / Pro / SS 95~120+mph

According to the specs provided, I was fit for the SF405 shaft. The SF stands for ‘Spec Free’ meaning that these shafts do not follow the conventional labeling system of R, S, X, and weight. The first few waggles and I was at a loss for words.

Dumina claimed that after three rounds with the Autoflex, I would be well adjusted and that results would be prominent. I began by hitting a few shots with the 43-gram shaft and immediately noticed that the shaft had something much more than meets the eye.

Once I got over the initial doubt that a whippy shaft would not be able to square up to the ball at impact and started to swing normally, the shots flew straight with a bump up in launch angle. The higher launch (from 9º up to 13º) gave me more carry distance over my previous gamer, but I thought it might be increasing my backspin. But a quick check with a launch monitor showed an average of 2,000-2,100 RPM, which was about the same as before.

But the most noticeable numbers were from the total distance, which was about 5~7 yards farther than my usual average. This was surprising because I felt I was swinging a little slower and smoother than before (it may be from the fear that the whippy shaft may cause a duck hook), but the average ball speed increased from 62~63mph to about 65.

I venture that because the shaft is more flexible, it causes the head speed to increase, kind of like cracking a whip of sorts. This somewhat fits into my current belief that a more flexible shaft hits the ball longer (at the expense of accuracy).

Pretty darn good numbers for me, but ZERO side spin means a straight as an arrow shot and 1.50 smash factor.


The numbers on the launch monitor were impressive for my standards and usual play. But it needed to be tested out on the course.

At the time of this article, I have played some 10 rounds with the new AutoFlex shaft on my Cobra F9 driver (10.5°, 45.25 inches at D2) and I couldn’t be happier with my results. My driving accuracy has significantly improved over the conventional shaft (HZRDUS Smoke 6S).

I’ve played in both fair and very windy conditions, and the results were the same. I was finding a lot more fairway than ever before. That pesky little draw at the end that rolls the ball into the left rough has all but disappeared.

To be frank, I didn’t see much change in the overall distance as well-struck shots from both my old gamer and new shaft tended to go about the same distance. However, it was the frequency of how often I was able to hit the sweet spot with the new shaft that made me feel much more confident in swinging the driver on the tightest of fairways.

I am still searching for the right words to explain it, but the driver feels whippy on the backswing and yet it feels like the entire length of the shaft firms up on the downswing and at impact. At times, I was certain that the shot completely missed the center of the face and a quick check confirmed that I struck the ball on the heel or toe, well outside the center. But the resulting ball flight is either a slight push or pull with a small distance loss of about 10 yards. Yet, no bananas or duck hooks that I’ve come to associate with such mishits and feedback to the hands. What sorcery is this?

But the most beneficial factor for me was that I was swinging the club much easier and with less energy exertion than I would have done with a heavier, stiffer shaft. I had a lower back disc surgery five years ago that prevents me from making a full turn and a limited finish. Playing with longer-hitting friends invariably leads me to try to swing harder at a faster tempo, usually leading to ballooning scores.

With AutoFlex, once I dialed into the new reality with an adjusted belief about whippier shafts, I was able to maintain both accuracy and distance for the whole round and not feel as tired. And I was better able to maintain my balance with a smoother swing and not have to worry about losing distance. Perhaps this is what let me hit the face center more often. Just like the namesake, it was as if the shaft was automatically trying to help fix my swing flaws to provide maximum forgiveness.

Whatever it is, I was sold.

I now have the same spec AutoFlex shaft in my 3-wood as well. If I had trouble getting my fairway woods up in the air previously, no one would suspect that of me now.

I would love to replace all of my shafts, irons and all if I could afford it, but unfortunately, the shafts are quite expensive. The company tells me that the “hidden technology” material and the manufacturing process is quite costly (nearly seven times over regular shaft manufacturing cost), and they are available in limited quantities at 950,000 KRW (about $775) each.

For me, the proof was in my new-found fearlessness with the driver and wood. I get a kick out of waggling my driver on the first tee to the shock of my playing partners and then bust a drive down the middle. Some still can’t come to grips with the shaft despite trying for themselves. And the makers of the shaft are keeping their lips sealed on what makes the shaft behave differently than the commonly held perceptions. In fact, Dumina has not applied for a patent at all, stating that once their secret is out, it will change the way we play golf and limit their business from copycats. So whatever KHT is about, it will remain undisclosed for the time being.

What do you think? Do you have any ideas on how the AutoFlex shaft works or what are its component materials? I would be interested in hearing from other gear heads out there!



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James is a golf gear-nut living and writing about all things golf in Korea. A fan of Tiger, Fred, and Seve, he is forever seeking the holy grail of golf clubs that will lower his score. He graduated from the University of British Columbia in Vancouver, BC, Canada and has been in Korea to witness the explosive growth of golf since 1996. Despite playing golf for over 30 years and being a perpetual 10-handicapper, James steadfastly claims to be the embodiment of the Average Joe Korean golfer. He can be reached at [email protected], and often introduces cool new Asia-based golf gear on YouTube and Instagram.



  1. Pingback: The ‘game-changing’ AutoFlex shaft: A year in review – GolfWRX

  2. T-Bone

    Feb 17, 2021 at 12:45 pm

    There’s a sucker born every minute.

    • Ryan O'Keefe

      Sep 22, 2021 at 1:02 am

      There’s a naysayer that’s happy to throw out unfounded statements without a clue about what they’re talking about, every minute.

  3. Pingback: The driver shaft that dominated the talk at Rory Mcilroy’s Christmas dinner – GolfWRX

  4. Pingback: Adam Scott testing Korean AutoFlex shaft at 2021 Farmers Insurance Open – GolfWRX

  5. s

    Dec 1, 2020 at 11:30 pm

    Black Pink, Rainbow. Names of the k-pop idols. Coincidence? LOL

  6. Ken

    Nov 30, 2020 at 2:34 pm

    Nice article James. Just purchased a sf405. For your fairway wood, did you use the same shaft and tip it or do they make a version of the autoflex for fairway/hybrid clubs. Thanks

  7. James

    Oct 16, 2020 at 10:36 am

    The AutoFlex shaft is now available to be purchased from Dumina Co. Ltd in Korea.Their site in English is at and they accept PayPal now.

  8. steve lee

    Oct 12, 2020 at 8:28 pm

    I send the e-mail to Jimmy
    hope I can order one in the US
    I don’t know If I should order Autoflex SF505 shaft / 51 grams or SF505X 54 grams

  9. Paul Davis

    Oct 12, 2020 at 3:47 pm

    The answer I believe would be in an ER chart of the shaft. Based on the description of the feel it seems like the version being tested may have a stiffer mid-section. This would be similar to the Graphite Design Tour AD MJ shaft lineup, but at a much lower weight class.

  10. Thomas

    Oct 1, 2020 at 7:57 pm

    Info on purchasing one please

  11. Wesley Yano

    Oct 1, 2020 at 1:36 pm

    I would be interested in possibly purchasing the SF405 shaft . Would you be able to provide information on how to go about purchasing it?

  12. Greg

    Sep 24, 2020 at 9:52 pm

    I saw this shaft use today my Matt at TXG and he gain ball speed , total Distance up club speed this Shaft is the Real Deal. Just hope the price could come down! At 63 of age with a105 club head speed love to try this Shaft out. Hope this Company can keep it a secret or get a USA Patient. Very nice Company . If you ever want a old Timer to try it I will try it.

  13. Jason

    Sep 9, 2020 at 2:49 pm

    It’s a very interesting concept. As a fitter I am always looking for new innovations to introduce my clients to. This one has a long way to go, but the concept is certainly interesting.

  14. ...

    Aug 20, 2020 at 12:21 pm

    7 iron spinning 3600rpm in the first video. useless on the course.

  15. George Steer

    Aug 17, 2020 at 12:45 pm

    Is $775 worth it if my back feels less strain and I can play longer into my senior years? ABSOLUTELY!

  16. Fishing Rod is the Future

    Aug 17, 2020 at 12:23 pm

    I always believed when everything else is equal, lighter the shaft is better. However, I never expected to see such a wimpy looking shaft to be stable during the swing. But, I think about it again – it makes a sense. Fishing rods are wimpy but stable. And, good fishing rods cost a fortune. They must be modeled after a good fishing rod.

    • James

      Aug 18, 2020 at 2:45 am

      Great observation. That is precisely what I was told 🙂

  17. Jack Nash

    Aug 17, 2020 at 9:48 am

    Question : Is it worth $700 smackers for me to gain 8 or so yards when my avg. drive is 220?

  18. Lee Ditiangkin

    Aug 15, 2020 at 1:42 pm

    Does anyone know where you can pick these up in the US

    • James

      Aug 16, 2020 at 8:54 pm

      Hi Lee.At the moment, the AutoFlex shafts are available in Korea only but I believe the company is looking for capable distributors in North America. I will update when and if they are sold there. If you are looking to purchase asap, email me for info to the company. 🙂

      • Jonathan Keith

        Aug 19, 2020 at 3:27 pm

        I would love to get one soon!

        • Lee Ditiangkin

          Sep 22, 2020 at 8:11 pm

          Just got the shaft. Couldn’t miss a fairway, something different about this one.

          Sometimes it appeared the shaft would break at the top of the backswing, but at impact felt pure. Took a while to get used to the flight of the ball because it takes off at a higher window.

          You can swing fast or slow, the shaft responds pretty much down the center.

          Going to play another couple weeks and want to practice with a trackman to see the numbers.

          Coming from a tpt 15, so this is a drastic change.

      • Michael

        Sep 24, 2020 at 7:45 pm

        Sent you a message James. Thanks.

      • Jerry

        Sep 24, 2020 at 10:33 pm

        I would like to get one of these shafts, im also dealer for different makes of clubs and drivers,
        How do I get in contact in getting these shafts?

      • Warren

        Sep 26, 2020 at 9:54 am

        Hi James,

        Thanks for the info and offer to share the company info. I am looking to purchase immediately.


      • Jason

        Sep 26, 2020 at 2:44 pm

        Hi James,

        I’m interested in buying one of these shafts – Autoflex SF505xx shaft

        – Can you please send me more information. Thank you!

      • Victor

        Oct 1, 2020 at 10:39 pm

        James…can you send me info on purchasing one? Current swing speed is 110+ and playing a 60tx pro orange. Recommendation on which one? Thanks.

      • Scott marshall

        Oct 7, 2020 at 3:09 pm

        James can I get company name to purchase one of these shafts ? Thanks

    • geohogan

      Sep 23, 2020 at 4:41 pm

      try ebay in two or three years for $300, with free delivery.

  19. Benny

    Aug 15, 2020 at 1:20 pm

    Great article. Fellas the Rogue 125msi sold for $1200 and many bought those shafts. Not applying for a patent means it cannot be controlled by a manufacture, that theyinvested something. So thisis something abvious and easy.
    I have always thought about a shaft that has to be installed in a specific way for each player, on their plane. That the walls are built up so not to allow the head to twist ever and only flexes backwards on the plane.
    If thats the case the more “whip” the better it helps and zero chance of misdirection or miss hits.
    Maybe its illigal and why its not been marketed. But if we do not play USGA golf than who cares?

  20. Paul Runyan

    Aug 15, 2020 at 12:10 pm

    I think I will wait for Ian and Matt at TXG to do some testing!

    This will probably work well for Some seniors, etc., but I would love to see Matt try this out in his new Callaway or better yet the old Ping G410.


    • gwelfgulfer

      Aug 16, 2020 at 1:05 pm

      Do a head to head with the Nunchuk to see who rules the one flex for all category.

      • geohogan

        Aug 23, 2020 at 12:29 pm

        Last I looked Nunchuk driver shaft sold for $250, and Xi iron shaft $60

        A no-brainer at 1/3 price.

    • ko

      Aug 17, 2020 at 4:22 pm

      Freaky diky mavericky

    • Sean P Momtahen

      Sep 24, 2020 at 4:49 pm

      Go check out their youtube… the review came out today and it pretty amazing TBH

    • Johnny Penso

      Sep 24, 2020 at 7:46 pm

      Video came out today. Matty gained an avg. of 20 yards through the air. Longest driver was over 370 yds.

  21. Walter E. Welky Jr

    Aug 15, 2020 at 12:01 pm

    Sounds like it is capable of flexing from 9 o’clock to 3 o’clock with zero torque. Is there an orientation mark on the shaft that would render adjustable clubs useless?

    • Daniel Whitehurst

      Jan 31, 2021 at 11:48 pm

      Not on a Callaway. The shaft doesn’t spin just the two rings around the sleeve. But bad for any other manufacturers adjustable sleeves though.

  22. TonyK

    Aug 15, 2020 at 10:50 am

    This made me curious.. We all know that there are illegal driver heads, but can there be any “illegal shaft” at all?

  23. jim

    Aug 15, 2020 at 10:17 am

    Those “in the know” have known this for years…..hardest part is trying to get golfers to get over their misinformations, personal feelings and preconceived notions as to what is going to happen during golf swing. Hit a 13* driver? what? no way, it will go to high !!! Not.

  24. Glenk

    Aug 15, 2020 at 7:28 am

    Excaliber shafts here in America has been doing this for years in wedge shafts to create extra feel and spin. They are now releasing this same concept in irons and soon woods – called rapid taper shafts. Hackers paradise reviewed the iron shaft and got 8 extra yards from this shaft with better carry numbers. Exxcaliber will not be charging ridiculous prices for theirs though thankfully.

  25. JM

    Aug 15, 2020 at 3:08 am

    When I was younger, I had no money and would buy clubs from Play It Again Sports. I found a nearly new Callaway Steelhead 3 wood for $80 and picked it up. I had no idea what specs were or even why they mattered. I loved that 3 wood. Straightest club in my bag and I always striped it. One day im playing with a good player and i crush my 3 wood. He asks to check it out and proceeds to tell me that it has a women’s shaft in it. I got rid of it immediately and have never hit a 3 wood that good since.

    • Rothkofan

      Aug 15, 2020 at 8:54 pm

      Freddie Couples gamed a 3 Wood for years…that he stole from Tom Watson’s then-wife

    • nomad golfer

      Sep 1, 2020 at 6:53 am

      One thing this article has done for me and that is my rejection of ladies flex has gone and I know where there is a lovely 7 wood (L) and I’m going to buy it tomorrow. I should have known because My old TM R7 and R11 have geriatric shafts and hit like winners. Thanks

  26. DPavs

    Aug 14, 2020 at 12:59 pm

    The price makes this a no go for the average golfer… so it’s a fail for me.

  27. dat

    Aug 14, 2020 at 11:13 am

    LOL $775 for a shaft?

  28. George Steer

    Aug 14, 2020 at 10:52 am

    Great article James!
    Does the company have any plans to market in the United States?

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Whats in the Bag

Talor Gooch’s winning WITB: 2021 RSM Open



Driver: Callaway Epic Speed Triple Diamond LS (9 degrees @8.3)
Shaft: Fujikura Atmos Blue 7 X (45 inches, tipped 1 inch)

3-wood: Callaway Rogue (15 degrees @14)
Shaft: Mitsubishi Diamana D+ Limited 80 TX

Hybrid: Callaway Big Bertha Alpha 815 (20 degrees @17.5)
Shaft: Aldila Tour Blue Hy 105 TX

Irons: Callaway X-Forged ’21 (4-6), Callaway Apex MB ’21 (7-9)
Shafts: Nippon N.S. Pro Modus3 125 X

Wedges: Callaway Jaws MD5 Raw (46-10S, 52-10S @51.5, [email protected], 60-08C)
Shafts: True Temper Dynamic Gold Tour Issue S400

Putter: Odyssey Tri Hot 2 Prototype

Grips: Golf Pride Tour Velvet

Ball: Titleist Pro V1

  • Featured image via Callaway on Twitter


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Whats in the Bag

Collin Morikawa’s winning WITB: 2021 DP World Tour Championship



  • Collin Morikawa’s what’s in the bag accurate as of the DP World Tour Championship. Photos c/o SMS on Tour.

Driver: TaylorMade SIM (8 degrees @9.5)
Shaft: Mitsubishi Diamana D+ Limited 60 TX

3-wood: TaylorMade SIM Titanium Rocket 3 (14 degrees)
Shaft: Mitsubishi Diamana D+ Limited 80 TX

5-wood: TaylorMade SIM2 (19 degrees)
Shaft: Mitsubishi Diamana D+ Limited 80 TX

Irons: TaylorMade P770 (4), P7MC (5-6), TaylorMade P730 (7-PW)
Shafts: True Temper Dynamic Gold Tour Issue X100

Wedges: TaylorMade MG2 (50-09SB), Titleist Vokey Design SM8 (56-14F), TaylorMade MG2 (60-08SB)
Shafts: True Temper Dynamic Gold Tour Issue S400

Putter: TaylorMade TP Juno Prototype
Grip: SuperStroke Tour 1.0

Ball: TaylorMade TP5 (2021)

Grips: Golf Pride Z-Grip Cord

More Collin Morikawa WITB

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Whats in the Bag

Webb Simpson WITB 2021 (November)



  • Webb Simpson what’s in the bag accurate as of the RSM Classic. 

Driver: Titleist TS3 (10.5 degrees, C2 SureFit setting)
Shaft: Mitsubishi Tensei AV Blue 65 TX (45.25″)

3-wood: Titleist TS2 (15 degrees, B2 SureFit setting)
Shaft: Mitsubishi Tensei CK Blue 70 TX

5-wood: Titleist 913Fd (18 degrees, B1 SureFit setting)
Shaft: UST Mamiya VTS 86 TX

Hybrid 1: Titleist 913Hd (21 degrees, B4 SureFit setting)
Shaft: Graphite Design Tour AD DI Hybrid 105 X

Hybrid 2: Titleist 915Hd (23.5 degrees, C3 SureFit setting)
Shaft: True Temper Dynamic Gold Tour Issue X100

Irons: Titleist 620MB (5-PW)
Shafts: True Temper Dynamic Gold Tour Issue X100

Wedges: Titleist Vokey Design Raw SM7 (52-08F, 56-14F), Titleist Vokey Design BV Proto 2021( 60-08K)
Shafts: True Temper Dynamic Gold Tour Issue S400

Putter: Odyssey Tank Cruiser V-Line

Ball: Titleist Pro V1

Grips: Golf Pride Tour Velvet

Past Webb Simpson WITB


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