Anybody ever heard or seen one of these? I've seen a guy at my local course screwing around with one, and was intrigued. I guess he forgot it on the green this morning, and when I was putting on my lunch break I gave it a try. It might be the most frustrating thing I've ever done, but there is instant feedback about my stroke that was really eye-opening. For less than $10 I'm going to buy it and see if I can get things back on track.
https://www.amazon.com/DYNWAVE-Putter-Putting-Balance-Training/dp/B07MDJVCZT
https://www.amazon.com/DYNWAVE-Putter-Putting-Balance-Training/dp/B07MDJVCZT