This is a replacement / spare headset adapter for your Yaesu FTA-250, FTA-450, FTA-550L, FTA-550AA or FTA-750L aviation transceiver.
This is a direct replacement of the Yaesu part SCU-15 that is now discontinued. The SCU-15 was the same thing but without the PTT connector.
Allows you to use any standard general aviation headset with dual plugs (PJ-055 and PJ-068) with your Yaesu transceiver. The Yaesu SCU-42 headset adapter now has a dedicated PTT connector to seamlessly incorporate a separate external PTT switch.