This specification covers shock absorption requirements for new and reconditioned football helmets for use in competitive play and practice. The parts of the helmet that will be in contact with the head should not be made of materials that are known to cause irritation or disease. The helmet, as tested, should have no rigid external projections greater than the specified dimension and any faceguard or faceguard hardware installed in the helmet must be removed prior to testing. All allowable external projections should be smooth and rounded while all internal rigid projections that can contact the wearer's head should be adequately protected by cushioning or force spreading. Internal shock-absorbing helmet components should not become detached or loose during impact tests or show any permanent deformation or physical damage.