Travel Trailer etc.Twist-and-Lock system.Display: 3-bits, LED digital tube, lamp display is optional (Red, White, Blue, Green, Orange) . It works for 5V-48V. Mini size and easy to install,work great for checking Voltage. With Touch ON OFF Switch,easy to use and save energy. Support battery voltage value and capacity percentage of battery display Touch about 5s to turn on or turn off the power. The state of your battery between full charged and discharged The meter has easy to read LED segments and connect to your 12 volt system. Used to monitor the storage-battery voltage, with reverse connection protection function, line will not be burnt. Timely grasp the state of battery voltage, voltage measurement purposes can also be used for other products.Package includes:1 x DC 5V-48V Voltmeter with Touch ON OFF SwitchSpecifications:Waterproof; Flame retardant material Measure voltage: DC 5V - 48V Size: 37x17mm Interface Type: Anode and cathode Eco-friendly Material: Plastic Item color: Black LED display color: Red, White, Blue, Green, Orange (Optional) Application: Universal for all Cars, motorcycles and other universal models.