Sennheiser SC 30 USB CTRL (505548) - Single-Sided Business Headset | For Unified Communications | with HD Sound, Noise-Cancelling Microphone, & USB Connector (Black) Single-sided headset Active Guard technology protects against acoustical shock Noise cancelling microphone filters out ambient noise for optimum speech clarity Ultra lightweight headset with large ear pads for increased comfort Call control units answer/end calls, control volume, Redial and reject incoming calls Sennheiser HD voice clarity - wideband sound for a natural listening experience Noise canceling microphone - filters out ambient noise for optimum speech clarity High-comfort - Single sided large ear pad in a lightweight headset for relaxed wearing Call control features: answer/end a call, volume up/down, microphone mute, redial last outgoing call and reject incoming call Bendable boom arm - ensures microphone position is always optimal. Cannot be twisted out of position Pivotable boom - rotates through 340 degrees for wearing flexibility on right or left ear and precision microphone placement ActiveGard - technology protects you from acoustic shock and sudden sound surges Peace of mind - 2-year international warranty