... FM transmitter , frequency (87.5~108.0MHz)selection, digital display irror display frequency, RF output stably, more frequency for selection, without interference ... , nice view, no blind spot, greatly increase the safety. 12. Directly hook on the back mirror, without occupation of space ... 1. Bluetooth version: V2.0 and A2DP 2. Working voltage: 12 to 24V DC 3. Frequency: 2.4GHz 4. Battery capacity ...