Bluetooth FM Transmitter 4.1: With Bluetooth 4.1 technology, the wireless FM transmitter automatically selects the vacant frequency (range from 87.5 to 108 MHz) without interference during music playback. Strong Compatibility: The car radio adapter works great with most Bluetooth-enabled devices like , , , and smartphones. Long Battery Life: Features a built-in 700 mAh battery that supports up to 10 hours of continuous transmission. You can enjoy your favorite music while traveling without worry. Friendly Design: Portable and easy to charge with a USB port; it notes the last FM transmission frequency. Easy to Use: Turn on the Bluetooth FM transmitter and tune the radio to the same frequency, then connect your handly/audio player to the modulator via Bluetooth. Color: Gray-black. Material: Plastic. Size: 10.4x7.1x2.4cm. Package Contents: 1 x Car Bluetooth FM Transmitter. Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture to differ slightly from the real one. The allowed measurement error is +/- 1-3 cm.