The UEGO gauge will indicate changes in the air/fuel ratio in real time, which is essential when you aim to perform safer, more powerful and accurate engine tuning. Specifications: 52mm(2-1/16") Diameter Mounting Compatible with Vehicle/System Voltages up to 16V 0-5V Analog Output Serial RS-232 Output 20ms Typical Response 8.0:1 to 20.0:1 AFR / 0.55 to 2.00 Lambda Configurable 3 or 4 Digit Precision Display Modes Configurable AFR, Lambda or O2% Display Modes Free Air or Resistor Trim Calibration Modes Auto Dimming Feature Gledewen Wideband UEGO Air Fuel Ratio Gauge Kit Includes: 1 * UEGO Gauge 1 * Wideband Oxygen Sensor 1 * PWR/IO Cable 1 * Sensor Harness 4 * Butt Connectors 1 * Silver Nut 1 * Installation Instruction Usage Steps 1. Connect Harness A to Port A. 2. Connect Harness B to Port B. 3. Connect the other end of Harness B to the sensor. 4. The other end of Harness A has a red wire for the positive terminal and a black wire for the negative terminal. 5. Connect to a 12V power supply. The instrument will start working, with a working voltage of 12V. 6. The dashboard has a setting and selection button, allowing for 8 function switches. 7. In the 4-digit mode, press the left button to switch to the 3-digit mode. Press the select button to confirm, which will change to 3-digit mode. Keep pressing to switch to the initialization mode or air-fuel ratio mode. 8. Change to CAN mode for engine combustion ratio calibration and adjustment. This can increase the combustion ratio and improve engine efficiency.