Parts & Accessories Smart Heads-Up Display (HUD) for diagnosing and monitoring car readings live, moment by moment. It's the best addition for monitoring engine performance and maintaining car safety. Features and Characteristics: Engine Temperature Display: To monitor water and radiator temperature promptly and avoid any sudden rises. Speedometer and Engine RPM: Clear digital display of speed and engine rotation rate. Fault Check: Read and check Diagnostic Trouble Codes (DTCs) and display car problems. Voltage Display: Monitor battery and alternator voltage. How to Operate: Very easy to install; just plug the dedicated cable into the OBD-II port located under the dashboard, and the display will automatically turn on and off with the engine.