Will fit all hard hats with universal accessory slots. Designed for added long-term comfort and increased protection. When not in use, the arms allow the ear cups to stand off clearly from the head.• Easy to attach and detach from helmet• Spring loaded arms provide an excellent fit to the ear• Soft foam ear cushions ensure comfortable wear• Durable polystyrene ear cups pivot and slide for a secure seal• NRR of 21 dB for protection against common industrial noise