This is an effective training tool for mastering proper arm rotation and body turn. You can practice safely anytime, anywhere. If you're looking for one, please consider this. PERFECT ROTATION LIGHT [From Reviews] I thought I was being fooled, but after practicing the business zone, it really improved, so I highly recommend this. Recommended for everyone, from those just starting to learn the triangle to those who have mastered it. I always use it at least once a month to keep the feeling fresh.