The adapter works with my David Clarke headset, but the volume is low and it uses batteries quickly. It came with no instructions: I discovered that unplugging the mic jack disconnects the circuit and stops the batteries from draining while not in use. The cable with the red tip is the mic in for the computer. Make certain that you select "microphone" and not "line in".
To solve the battery problem, I decided to modify the adapter by buying a few parts from Radio Shack:
- Added connector for use with an AC/DC transformer (9 volt, 1 amp)
- Added on/off toggle switch
- Added LED to show on/off status
To solve the volume problem, I ran the sound through an external amplifier before routing to the headset.