This is an FSL-21 car audio adapter with AUX input, used in a Legacy BP5. It allows you to connect your smartphone to the McIntosh audio system and listen to music. It's a rare item because it's discontinued! I'm selling it because I've changed cars. It was working perfectly fine until I removed it. The instruction manual isn't included, but you should be able to find images and connection instructions by searching on sites like Minkara. RCA cables are included. - Model: FSL-21 - Input Type: AUX Input - Made in Japan