Simply insert these little ear plugs in your ears then decide which mode you want to be in: First, push the button in to open the valve- you’ll hear sound clearly and naturally- almost seems as if your ears aren’t even plugged. Then when loud sounds hit your ears, the Dynamic Sound Valve™ will automatically screen those sounds out protecting your hearing. Second, simply close the valve by pushing in again for total hearing protection. These are small, handy, and can go anywhere with you. Make the AXIL X-PRO your go-to passive protection! Features: Noise Reduction Brand: Axil Manufacturer Part Number: PLGSXPRO