PAC AAI-GM12 Auxiliary Audio Inputs and Interfaces for 2003 GM Class II: * Allows direct interface of any pre-amp level audio source to a factory radio with a slave unit, eliminating the need for sound-degrading solutions like an FM modulator * Interfaces input sources from DVD, VPC, MP3, satellite radio or PlayStation * Lower cost and higher quality sound than an fm modulator * Comes with a 3-position switch between 2 AUX inputs and the factory slave unit * High-quality audio isolation IC eliminates engine noise * Internal CMOS electronic switching for long-term reliability * Requires factory XM radio receiver, factory DVD rear seat entertainment or factory/aftermarket CD changer * In order to work, slave unit must continuously be playing or XM radio or DVD must be on * For 2003 GM Class II