Hosa GMP-112 is an adaptor designed to adapt a stereo phone plug to a mini stereo phone jack. It is ideal for use as a headphone adaptor.
Mono 1/4" Female to Stereo 1/4" Male
Female end accepts a mono signal and applies it to both Tip and Ring contacts at the male end. Use it to send a mono signal to both Left and Right contacts in a stereo 1/4" jack. Also can be used to "trick" and audio mixer's insert (sent / return) jack into behaving like a direct output.