When installing an aftermarket radio the AX-TOY28SWC will allow the user to retain their factory installed steering wheel controls without having to splice into factory wiring -(ASWC required and sold separately). In addition we included RCAs to allow the user to retain their factory installed 3.5mm jack. Aftermarket radio must have Aux in. This is an optional harness. Main power harness is still required. Retains Factory Steering Wheel Controls . ASWC-1 required and sold separately . RCAs included to retain factory installed 3.5mm jack .Aftermarket radio must have Aux in.