Amazon.com: Sennheiser Consumer Audio PC 7 USB - Mono USB Headset for PC and MAC, Black (504196) : Electronics
Amazon.com: Sennheiser SC 135 USB (508316) - Single-Sided (Monaural) Headset for Business Professionals | with HD Stereo Sound, Noise-Canceling Microphone, & USB Connector (Black), Adjustable : Electronics