For plantronics a22 e10 m12 p10 s20 ca40 p10 p10h ideal for listening in to calls for training and coaching purposes this adapter trainer cord with microphone mute switch and quick disconnect clamp will allow for supervised calls for maximum effectiveness 4 pin quick disconnectqd only plantronics mission is to enhance personal communication by allowing you to be more productive safe and comfortable youll notice a marked improvment in the clarity of your daily communicat