The protac ii"s active-volume function keeps you in touch with your surroundings while effectively protecting your hearing from harmful noise and impulse sounds like gunshots. Harmless sounds come through with no problem and weak sounds are even amplified, so you hear better with a protac than without hearing protection at all. It automatically shuts-off after two hours if no function is used. the headset features audio input for a mobile phone, portable phone or com-radio, a standard chassis jack for connecting flex cords. When an external audio signal comes in, the radio volume is muted and the external source determines the volume. Soft, wide, foam and fluid-filled ear cushions and individually sprung headband wires of stainless sprung steel provide an even and consistent distribution of pressure around the ears for the best possible comfort