Adapter for Stereo Headphones or Earphones to Mono Audio Equipment

3.5mm Mono-to-Stereo Adapter - Part No. M2SA

Plug Stereo Earphones into Mono Audio Devices

Listen to that older Radio or Tape Recorder using your Stereo Headphones
Will enable you to listen to Mono Audio in Both the Left and Right Ear of your Stereo Headphones that you might otherwise hear in only one ear
If you're converting your old recordings to record onto a stereo disc or tape, you'll want one of these
Plug Stereo Earphones into Adapter, and then Plug the Adapter into Your Mono Audio Equipment
Enables Stereo Earphones to Hear the Audio in Both Ears when Plugged into a Pocket Talker Audio Assist Device
I use it when I listen to my dictation recorder (scroll down to see picture below). The tape recorder is mono and the headphones plugged in through the adapter are stereo headphones

Specifications
Input Jack - 3 Conductor Stereo 1/8-inch (3.5mm) sub-miniature jack
Output Plug - 2 Conductor Mono 1/8-inch (3.5mm) sub-miniature plug
Size - Adds 1-inch of length to the plug going into your audio device
Color -Black