The pair of iron man rings is made from heavy-duty plastic. The rings are formed for an easy hand grip. Also included are 2 lengths of ouchless chain. Weight limit: 75 lb. ASTM certified. Requires swing hanger model No. NE4464-1 for wood set, or swing hanger model No. NE4463-1 for metal set. Parents caution children against twisting chains. This may weaken chains and cause failure.