A wide range of compatible applications Simple operation at a glance, one key single on / off backlight / sleep Intelligent detection prompt ABS flame retardant environmental protection material, high temperature resistance Master it at any time and anywhere, light weight / small size / built-in lithium battery / portable belt It integrates a variety of powerful functions and functions Professional precision LCD industrial appearance, simple operation, backlight function and long energy storage HTN wide viewing angle LCD green backlight Large capacity and easy charging 3.7v/1000mah standby lithium battery type-C charging interface A wide range of compatible applications Measuring 18650 lithium battery Voltage and internal resistance of AA / AAA alkaline battery And displayed by LCD Size: 156 x 63 x 36mm Calibration method: After dismantling the back panel, remove the marked ones first. Gently push up from the front LCD position, and then reversely remove the red wire on the back, so that it can be removed Then find a way to add a standard voltage of 5V between V+ V-. Press the button again to turn on the product to see if the voltage can be displayed normally Then just remove the battery Short-circuit the two points on this side, then plug in the battery, and the meter will automatically calibrate. After the calibration is successful, you can install it back as normal. Colour: black Material: plastic Package Contents: 1 x digital display tester (Due to different batches, the appearance of the product may be different, but the function is the same)