DROK Micro LCD Digital DC7-20V Voltmeter Panel 2 Wires 3 Digit Volt Meter Gauge Battery Voltage Monitor Tester with Bright Blue Backlight and Back-cover for Car Vehicle Electromobile Battery Checking Wide voltage managing range (DC7-20V), high stability and accuracy. Small size (79x43x25 mm) with back-cover, easy to install. No need extra power supply and 2-wire connection, simple and convenient. With reverse connection protection to prevent the meter burning , hence safe for use. Please dont expose the meter in direct sunlight for a long time, or the screen will be shut down.