PC9-401-KIT with PC5-90 Audi Active speaker Harness Adaptor ISO with power lead. Audi Rear Amplified ISO Adaptor. A harness adaptor lead allows you to install a car radio of your choice with out cutting any of the existing car wiring. All harness adaptor Leads are ISO ended and will plug directly into most models of car radio. This adaptor is not an off the shelf item, and is modified by CAT to connect required Amp Remote wire on Red connector with Blue wire on ISO block, it also comes with short tail on yellow battery wire and long red tail on Red ignition switched feed, which can either be connected to yellow, or to a vehicle ignition switched feed, not normally present at the back of the radio. Comes complete with Antenna filter and wires connected for plug and play usage. Use this harness where you have four wires in the Brown ISO connector. See Additional Information for Vehicle Applications.