Gath Hat Size M Fits 22 - 22 5/8" Head (56-57.5 cm)- Other sizes/colors available Gath helmets are made from quality materials to strict specifications and are built to last and are backed with a 3 year warranty. All materials are strong, durable, rust proof and will withstand harsh climate conditions and temperature extremes. Shell ..UV stable, impact resistant, quality ABS plastic. Liner.Multi impact washable EVA closed cell foam.