HUNTER Speed Ball Boxing Cow Hide Leather MMA Speed Bag, Muay Thai Training Punching Dodge Striking Bag Kit with Hanging Swivel, Workout High quality Cow hide leather Speed Bag Has an inflatable bladder inside which is pumped using a normal football pump. Tie design allows bladder to be replaced. Swivel can be fixed to any suitable surface. Comes with HUNTER swivel has a reduced center hub for speed/balance and rhythm of ball action and constructed with quality bearings this allows a Speed Bag to move freely in the direction of force thus allowing a fast and continuous strike rhythm when hit.