Sennheiser CC510 Lightweight Monaural Headset w/Noise Cancelling Boom Microphone. Independent double-sided headband adjustment and self-adjusting ballmounted speaker capsules allow perfect fitting to the head. Ultra Noise Canceling blocks out a maximum of ambient noise making your voice easier to understand. Ideal for professionals who need to keep in touch with what is going on around them and for extended periods of heavy-duty use.