Makes it easy to BRIDGE your 2nd (or bag) Cicada Audio® DSP600.4D / CX600.4D amplifier to provide a BRIDGED signal from the stock HD OEM radio REAR output into your Cicada Audio® amplifier. No cutting…. just PLUG-N-PLAY! NOTE: you must have the 4-channel output plug/harness currently on your stock HD radio with the appropriate output harness for this to work.