Specifications: Digital frequency scope: 88.1, 88.5, 88.9, 89.3MHz (88 ~ 108MHz can be customed) Frequency response: 20~18KHz Transmitting distance: 5-10m or above. Input port: F3.5mm solid pin Input resistance: 1K ohm Power consumption: 2 AAA alkaline batteries, more than 150 working hours Net weight: 32g; 47.5g(with batteries) Gross weight: 350g. User guidance: 1. Turn on the unit: Press the POWER key for 2 seconds, the indicator LED for self-checking frequency will light up. 2. Choose frequency: Shortly press the SCAN key to choose a frequency among 88.1, 88.5, 88.9, 89.3MHz. 3. Plug the connection pin of the unit to the 3.5mm audio jack (MP3 player, CD, DVD, MD, iPod, etc), turn on the audio device. 4. Adjust the frequency of the FM radio to the same frequency of what the unit has been set. 5. Turn off the unit: Press POWER key for more than 2 seconds, the indicator LED will go out, the unit turns off.