Finally a pair of earmuffs that fit under a welding helmet!!! The 3M earmuff H505B is designed to be used with 3M Speedglas auto darkening welding helmets, like the Speedglas 9100. The H505B 3M earmuffs meet the needs of most welding industry applications but please review your individual circumstances before making a decision. Personal protective equipment (PPE) is an essential part of good welding safety. Buy 3M Personal Safety Products, Speedglas auto darkening welding helmets and spares online from Eweld - your number 1 Australian online welding helmet shop!!