Main PCB for the iPort IW-21 and IW-22. Can be used to upgrade IW-2 through IW-5 with the following features: Charges all compatible iPod/iPod touch models except for 3rd-generation iPods. Selectable variable audio output. A built-in audio preamp allows the iPort to control the iPod"s volume via IR or from the iPod when in the general control mode. Selectable component or composite/S-Video output. Selectable default iPod control mode (general or extended). Main PCB authentication unlocks the video output on the iPhone 3G and 2nd generation iPod touch. The ability to update iPort firmware via the optional Firmware Update cable (part # 70132).