... is optional); 4, 9" Car Portable PC Headrest Model No.: HB902PC (9" Car Headrest Active/Portable Car PC Android 2.3 DDR2 ... )1, 8V-16V Wide Voltage;2, USB/SD Reader (up to 32G);3, Built-in ... Wifi function (3G is Optional);4, Built-in Speaker and FM/IR Wireless Transmitter ... Screen with touch pen for easy operation. HB902PC 9" Car PC, In-Car PC, Car Auto PC