Connects directly to USB port (USB 2.0/1.1 compliant). No sound card required. Dual receivers with stereo sound. Dielectric construction. SED® lightweight noise attenuating earcups provide consistent, comfortable protection and superior sound quality. Unique combination of 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. Available in pewter or high visibility yellow earcups and special order colours.