This 7" across training bag is made of heavy canvas, Filled with BB(5 Lbs). it is a conditioning bag for all martial arts especially kung fu. the bag is swings freely from a heavy duty chain to help improve your eye/hand coordination while strengthening and toughening your figers and hands. You can also use it for:Hitting it-to train your iron palm. Striking it-use the included train(40 inches), hang it up and practice your striking techniques. Throwing and Catching it-to improve your fingers, wrist and forearm power.