I have not used them, or anything like them.
However the first thing for me, is that it promotes your eye to follow the club head, rather than the ball.....and I talk as someone who has spent ages making sure the club head follows a certain path etc and who struggles now to not watch the club head and instead focus fully on watching the ball the whole time.
I always found a second ball placed about 6 inches back and slightly outside the ball you want to hit as a better method of promoting the in to out swing. You dont need to watch it, just make your muscles and swing do it or else its billiards at the range.
That was how I was taught to do and practice it. I just wish I had never started to watch the club head path and takeaway.
