I purchased one of the 12ga harnesses this past winter in order to install a musical air horn in my truck. The horn required 12ga wiring for power, as it drew 20amps, but only came with a relay. Rather then figure out how to wire the relay, connecting the power and switch, and having to buy a switch and fuse holder, I simply purchased this BlackOak harness which was already pre--wired. I simply removed the connection for the light and spliced the positive and negative leads to the compressor of the horn. This harness made the horn installation very simple and appears to be fine quality as well. The BlackOak tech was very helpful in directing me to this purchase. And I couldn't find any other company of the internet which offers a complete wiring harness with 12ga wiring.