The Stereo Source to Transcom II Adapter is a cable that allows you to connect a stereo audio source, such as an MP3 player or smartphone, to a Transcom II intercom system. The adapter has a 4-foot cord, and one end is equipped with a stereo jack that plugs into your audio source, while the other end has a U-174/U plug that connects to the Transcom II system. This adapter is useful for pilots who want to listen to music or other audio while flying, as it allows them to easily connect their devices to the intercom system and share the audio with their passengers or other crew members.