Nulaxy Wireless in-Car Bluetooth FM Transmitter Radio Adapter Car Kit W 1.44 Inch Display Supports Tf/SD Card and USB Car Charger for All Smartphones Audio Players 1. THE BEST: Consolidated for customers the best FM Transmitter on the market the Nulaxy KM18 won the market for its superior quality and reliability. 2. GREAT ADVANTAGES: Compatible with most devices on the market. Play your favorite songs on your car stereo through Bluetooth, TF Card, Aux Cable. Advanced noise reduction technology will ensure quality, crystal clear sound. 3. BIG LCD DISPLAY: 1.44 inch screen to better visualize phone calls, music, car battery voltage. The ideal screen size to assist you in driving safe without disturbance. 4. TECHNOLOGY IN YOUR CAR: 1) Bluetooth connection; 2) Answer phone calls with the press of a button; 3) Voltmeter function to monitor the quality of your car battery; 4) 3 different ways to play music in your car, and more. 5. SAFETY FUNCTIONS: Safety first. KM18 is equipped with a voltmeter to show you the condition of your car battery. Voltage should be between 13.2V to 14.7V when your car is on and moving. 12.2V to 12.8V when your car is parked and ignition is off.