External power supply: 12V or 24V DC power supply via vehicle battery; Overload protection current: 8A; range: DC 3.5-36V; Line length: 4.5 m; Accuracy: 2%; Rated current: 1-8A; Working temperature: -10C to 60C; Relative humidity: 80%; How to use: 1. Unplug the tester connection wire. 2. Connect the red clip to the positive terminal of the battery and the black clip to the negative terminal of the battery. The blue display shows the current battery voltage value. Turn on the front light. If connected in reverse, the voltage value is not displayed, but the lamp remains on. Self-test: Before using the tester, perform a self-test to verify equipment functionality. 1. Press the tester button to the () position. The LED on the instrument lights red, indicating the probe outputs positive voltage. 2. Press the tester button to the () position. The LED on the instrument lights green, indicating the probe outputs negative voltage. 3. Release the button and touch the probe to the positive electrode of the battery. The LED lights red, indicating the measured node has a positive voltage. 4. Release the button and touch the probe to the negative electrode of the battery. The LED lights green, indicating the measured node has a negative voltage. 5. Press the tester button to the () position. The LED lights red, then quickly touch the probe to the negative terminal. Color: Black + Blue Material: ABS Package Contents: 1 x Electrical circuit tester Note: Light reflection and different displays may cause slight color variations between the image and the actual item. Measurement error allowance is 1-3 cm.