Converts (PJ-051) Plug to Two (SC-838) Female Connectors. A Y Cord Adapter is required to connect any David Clark Series 3000 Noise Attenuating Headset to an aircraft that is equipped with two external jacks for access to the aircraft's intercom system. This addition makes the Series 3000 Headsets more versatile. This cord is great for training applications. Allows two headsets to be plugged in simultaneously.