Just used it for the first time today inside. It's a very interesting aid because of it's simplicity. I thought it'd be easy because the center white line is "carved out" a little. I thought it would act like a track. I think it has to, to some extent, which makes it a little frustrating when I hit one of the bearings.
I have a very difficult time seeing the aim line - one of the reasons I use the putter pictured. I usually line up the arrows on my ProV1x's from behind the ball and when I get over the putt, I swear it's not aimed where I want - I get back behind the ball, yep, it's right - get back over the ball, nope it's not.
Even with my eyes over the ball evidenced by equal space between the ball and the lines on the putting-tutor + the long white line track, I am still surprised to see the ball end up where it comes to rest when I make it cleanly past the ball bearings.
I got down to ground level and aimed the pelz line to my coffee mug, get up over the putt, and it doesn't look right.
So, I think this will go a long way to help me re-train my eye if I use it enough.
I never hit the left (inside) bearing. I hit the outside right bearing. I learned that I was decelerating. As soon as i started accelerating into impact, I was making it cleanly past the bearings with consistency. It took me a while to realize it as I tried different ball placements and grips. It was nice to see I could use my favored lead hand low grip, accelerate and hit a solid, square putt.
Can't wait to take it to the putting green once the weather clears up.