Everlast Cardio Strike Bag (Black) Freestanding strike bag helps built endurance and agility for boxing and overall fitness training Comfortable striking surface of synthetic polycanvas around an inflatable air bladder High-density plastic base fills with water or sand for stability Durable spring neck creates quick bag rebound; EverFlex collar system absorbs impact Weighs 70-pounds when filled with water; measures 63 inches tall at highest setting; includes foot pump