**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 Disconnect/QD only) Plantronics\' mission is to enhance personal communication. By allowing you to be more productive, safe, and comfortable you\'ll notice a marked improvment in the clarity of your daily communications.