This product can only be used on substrates made of three materials: iron, aluminum, and automotive steel plates, and cannot be used on any other materials such as stainless steel, plastic, etc. When starting up, the machine should be at a distance of at least 20cm from the object being tested or any metal substance, as well as electronic products in operation. The of the object being measured should be smooth and flat, without any depressions or protrusions, and without any foreign objects covering or obstructing it, otherwise it result in inaccurate measurement After use, please remove the battery and store the product in a dry environment, being careful to from any magnetic objects and working electronic products note:When in use, if multiple measurements are taken at the same point and the thickness indicator light sometimes displays green and sometimes displays orange, it indicates that the thickness of the film/paint coating at that point is around the critical value of 180um,rather than a product quality issue; Similarly,if multiple measurements are taken at the same point and the thickness indicator light sometimes displays orange and sometimes displays red, it indicates that the thickness of the film/paint coating at that point is around the critical value of 400um,and it is not a product quality issue Measurement range:0-1800m/0-1.8mm/0-71mil Measurement error:100m/0.1mm/4mil Minimum diameter of substrate:50mm Minimum thickness of substrate:0.5mm Working temperature range:18C-30C Working humidity range:10-80%RH (The product printed words depending on the batch, but this does not affect use) Color: As Shown Material: ABS Package Contents: 1 x Car Paint Thickness Tester 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.