2-to-4 channel standard sound adapter harness with antenna bypass switch

Functionally equivalent to BMW part number 65-12-1-379-329, and adds an antenna bypass switch

Plugs into fader connector of a 2 channel standard / radio-only audio system. With this adapter you can run an OEM 4 channel radio like the CM5908 or KE83-ZBM without a trunk amplifier in a car with 2 channel radio-only wiring.