SED® lightweight noise attenuating earcups provide consistent, comfortable protection and superior sound quality. Dual receivers provide a crisp audio response. The microphone preamplifier operates over a voltage range of 4V to 24V and a load range of 100K Ohms. An adjustable behind- the-head steel tension band and two fully adjustable velcro straps provide day long wearing comfort and a secure fit even under a hardhat or helmet. With preamplified dynamic boom mic, volume control, nexus connector and 15' cord.