MP3 Player Unit Set For those who can install it, and for those looking to add to their existing setup. It's space-saving, so it can fit in tight spaces. For those who don't have SD cards, Micro SD cards, or USB media. Basic wiring is easy. I bought it with the intention of simply adding speakers. This is for those who understand this. Includes: Main unit Remote control Instruction manual Everything shown in the photos. It's not expensive. How about using it for expansion, etc.?