This is an ONKYO portable MD player. * I have confirmed its operation. It works without problems when the adapter is plugged in, but it did not work with only the rechargeable battery (gum battery). I don't know if the battery is old, but I don't think it can be used for portable use. * I used it with a car cassette audio system, so I will also include the car adapter. (I can't confirm its operation now because I can't use cassettes in my car.) Please consider this only if you understand the above.