Bluetooth FM Transmitter 4.1: With Bluetooth 4.1 technology, the wireless FM transmitter automatically selects the free frequency (range from 87.5 to 108 MHz) without interference during music playbackStrong compatibility: the in-car radio adapter works great with most Bluetooth-enabled devices such as , , , and smartphonesLong battery life: has a built-in 700 mAh battery that supports up to 10 hours of continuous transmission. You can enjoy your favourite music while travelling without worryFriendly design: portable and easy to charge with a USB port; it notices the last FM transmission frequencyEasy to use: turn on the Bluetooth FM transmitter and connect the radio at the same frequency, then connect your handly/audio player to the modulator via BluetoothColour:Gray-blackMaterial:plasticSize: 10.4x7.1x2.4cmPackage Contents:1 x Car Bluetooth FM TransmitterOnly 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 a little different from the real thing. The measurement allowed error is +/- 1-3cm.