Function: The difference between the 1W version and the 2W version is that the power of the power amplifier tube is different, and it is the same if it is farther away from 2W. Product specifications: FM transmitter board FM transmitter Transmitting frequency: 76-108MHZ Supply voltage: 12V Second harmonic: -40DB Output power: 0-1W version 0-2W version continuously adjustable (manual) Working current: 0.25-0.3A for 1W version, 0.4 to 0.45A for 2W version Board size: 8.5cm*4cm Volume: 30 levels adjustable Audio input: 3.5MM headphone jack (plug in the headphone plug to automatically connect to the external audio source while disconnecting the built-in MP3 audio source, unplug the headphone plug to automatically access the built-in MP3 audio source) Antenna interface: SMA female (need to be equipped with an antenna) Standing wave protection: The board has no standing wave protection Transmitting distance: depends on antenna height and antenna gain (with GP standard antenna height 6 floors above 3KM) MP3 player: (The following functions require remote control operation) 1. Support WAV MP3 format. 2. Auto play after power on. 3. Memorize volume and track after power down. 4. Support 32K-320K rate 5. Support maximum (32G) SD 6. Auto play after boot 7. EQ function, normal, rock, pop, classical, jazz, etc. Shipping list: 1PCS X76-108MHz transmitter FM transmitter board 0-1W-0-2W 2000m transmitter module