I bought my HU through Crutchfield. They threw in the harness and adapters for free. They included detailed written instructions and free lifetime tech support, which I phoned once and the tech support person was excellent. I bought my speakers and amp elsewhere but Crutchfield's HU price was as good as any out there. Depends on the model. Worth it to get at least one piece from them for the freebies I mentioned above. Good luck.