The standard size and heavy duty construction of this punching bag provides the ideal target for building muscular endurance and mobility. A 1" closed cell foam liner is included in all of our filled bags to help eliminate hand injuries. Springs are suggested when hanging bag from home rafters/support beams to minimizes the shock to home structure. For more information please visit our Ringside website section: Punching Bags, Stands/Bag Hangers. Types of hanger needed depends on substrate from which the bag is hung. For more details visit our Stands / Bag Hangers Section.