The listing, Sony cassette adapter w/DC power cord has ended.
This is a Sony Cassette Adapter (with power cord), for a CD player or other such device.
If you have only a cassette player in your car and want to hook up another audio source, such as an mp3 or CD player, this is one way to do it.
This may work on other cassette players allowing a "line in" sort of effect, but I am not sure of the quality of the sound - nor do I know if this really works, since I don't have a car deck to try it in.
Seems simple enough and it appears to be in good shape physically ... I believe the power connector works, as I tested it on my "jump start" unit that I use for emergency lighting.
I can only accept Paypal, due to very low funds, and I'll pack this as best I can so it arrives to you safely.
Happy bidding, and have fun ! :)