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 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, the marked first. Gently push up from the front LCD position, and then reversely 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-. the button again to turn on the product to see if the voltage can be displayed normally Then just the battery Short-circuit the two points on this side, then plug in the battery, and the meter automatically calibrate. After the calibration is successful, you can install it back as normal. Colour: black Material: plastic Package Contents: 2 x digital display tester (Due to different batches, the appearance of the product may be different, but the function is the same) Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.