The Nordesco AquaDisk is a training tool that uses water resistance for the workout. Made of EVA molded foam, the ergonomic design of the grip insures a safe workout without putting stress on the shoulders. The AquaDisk can be used in a wide variety of exercises for the arms and shoulders. In deep water, use it in conjunction with the Nordesco Aquafitness Belt. Sold by the pair. Small disc is 7" wide x 1.5" thick with 1-5/16" finger holes. Medium disc is 8" wide x 1.5" thick with 1-5/16" finger holes.