This is a simple training aid to help windmill pitchers.
Windmill pitching is a pitching style used by fastpitch softbqll players everywhere. I would say that it is now considered the best pitching style to use for fastpitch softball.
It fits on the pitchers thigh, and gives them a physical confirmation that they have keep the arm close to their leg as they go through their pitching motion.
To see the Windmill Pitcher Website CLICK HERE