BOTH OF THESE HAVE BEEN DISCONTINUED! Sennheiser PC 26/36 Basic Info The PC 26 is monaural. PC 36 is binaural. Otherwise they are exactly the same. Integrated USB soundcard Noise canceling microphone USB plug & play – simply plug into your computer’s USB port and go Convenient 3-in-1 control – fully adjustable in-line volume/mute Free HeadSetup software – conveniently download Sennheiser software for easier control of your PC’s softphone from the headset Comfortable headband Flexible boom arm - PLEASE NOTE: The boom is for left ears only, it does not swivel 180° to be used on either ear Light and comfortable