For the first time,You need to download the APP application to the phone.You can scan the QR code on manual for your smart phone systerm Only Three Steps To Start It :
1,Press and hold the multifunction button 8-10 seconds, switch voice prompts in English or Chinese.
2,Adjust your transmitter and car radio to the same FM station to avoid noise.
3,To make sure the perfect sound, don't adjust the sound volume of the your car speaker to maximum; If you need louder sound, you can adjust the sound volume of your phone or FM Transmitter.

Specifications:
Bluetooth Version: V3.0+EDR
Frequency: 20 h- 20KHZ
USB Charging Port Output: 5V/2.1A
Sensitivity: -42db+ / 3db 360
Voltage: 5 V + / - 0.5
Working Current: 45mA (Max)
Stand-by Current: 25mA (Max)
Frequency: 2.402 ~ 2.480 ghz
Effective Range: 5meters
Sensitivity: -92 dBm
RF Output: 4 dBm
Frequencies:
FM: 87.5MHz-108.0MHz
Transmitted Power: 87 dBuv / 107 dBuv
Effective Range: 2 Meters

Package included:
Bluetooth FM Transmitter*1
Audio cable*1
User Manual*1