Plantronics Y training cord with mute switch (part #27019-03) for use with Plantronics H-Series Headsets; allows two headsets to function off one amplifier (M22). Also known as the supervisor's adapter cord. Comes with in-line mute switch. Quick Disconnect attaches to two quick disconnect headsets (H-series, P-Series or Plantronics Cisco Headsets). Both headsets can listen, but only one headset have a live microphone. The other microphone is muted. Key Features: For use with Plantronics H-series headsets, plantronics qd headset as well as cisco phone headset Easily connects at quick-disconnect connection Toggle switch mutes one headset It can also be used with Plantronics Polaris Headsets as well as any Plantronics Headset with a QD (Quick Disconnect) end Old Poly part # 27019-03 New HP part # 85S07AA Important Note: NOT compatible with wireless headsets Note: The red toggle switch allows the supervisor to control which microphone is live and which is muted. So only one microphone is live at any given time.