This class 4 helmet mount hearing protection is a good quality general purpose earmuff. The E style fitting is compatiable with the industrial Petzl helmet range±It features the following:±¥ Designed for medium noise levels.±¥ Lightweight and comfortable. ±¥ Liquid and foam filled cushions.±¥ Simple and strong height adjustment. ±¥ Replaceable cushions and foam. ±¥ Stainless steel headband wires.±¥ High visibility cups.±¥ Headband version is also available.