I found more info:
• Original car CDC port set aside , simple and quick to install
• Built-in high quality (18 bits,low noise) MP3 / WMA Decoder
• Supports USB Stick / SD / MMC card / flash drive / mass storage device / external harddrive
• FAT 16/32 system supported with up to 32GB capacity
• Higher than CD quality sound of your MP3 files with level-matching technology
• Full control over the music via steering wheel or head unit controls
• Super directory management, a directory corresponding to a CD in support of accurate memory without power.
• Additional audio 3.5mm Male to Male cable to connect any MP3/Audio player
• Playlist positions are preserved for several USB sticks
• The device and other original cd changer are switchable , make full use of the original equipment.
• USB port available for 5V 500MA for power supply from other equiptments like Mobile, PSP and so on in the use of charge purpose .
/Usb/sd/aux/ipod/iphone Car Kit for 17pin BMW E36 E46 E39 E38 /K1200lt/z8/z3/x3 Etc -Huahee
Power supply: 12V
Frequency: 20Hz to 20kHz, ±2dB
Power consumption: ≤1W
S/N ratio: 95dB
Working Temperature : -10C - 80C
Product dimensions: 94 x 66 x 16mm
Net weight: 80g
Gift box dimensions: 132 x 50 x 215mm