Elevate your game today with the Decker Sports VDB/SVD protocol system. Backed by science and research, you can increase your throwing velocity by 7MPH or MORE training with the VDB/SVD protocol system. Each set of underweight, regulation weight and overweight baseballs/softballs come with a pamphlet outlining the science supporting the training. Also included is a laminated detachable card detailing in-season and off-season training. This system is designed for all position players, not just pitchers.