1、Since the auto mode has built‑in data, the user can no longer perform calibration. In the auto mode, the coating thickness of iron, aluminum, and zinc substrates can be directly measured, suitable for measuring the coating thickness of automobiles. 2、User mode calibration does not affect auto mode. The critical thickness of the instrument for metal substrates (≥0.5mm). 3、According to user model calibration, the substrate diameter should be ≥50mm, and the substrate thickness should be ≥0.5mm. 4、Clear button design, convenient for operation, easy to select mode. Please note that this product can only be used to measure non‑metallic coatings. 5、Adopts high quality material, safe and eco‑friendly, firm and durable. Light weight and portable. 1 x Thickness Gauge1 x Abutment1 x Manual6 x Coating Thickness Film Condition: 100% Brand NewItem Type: Coating Thickness GaugeMaterial: Plastic + Electronic ComponentsTarget Measure: The thickness of the non-metallic coating on the metal surfaceMeasuring Range: 0~ 1.80mm / 0~ 71.0 mil non-metallic coating on metal surfaceAccuracy: ± 0.1mmPower Supply: AAA Battery x 2 (Not Included)Minimum Base Diameter: 50mmCritical Base Thickness: 0.5mmDisplay Resolution: 0.01mm / 1milWorking Temperature: 0~40°CWorking Humidity: 10~95%RHProduct Size: Approx. 6.2 x 3.5 x 10.5cm / 2.4 x 1.4 x 4.1in (±1-2cm)Description: 1. Since the GM200A vehicle model has built-in data, the user cannot perform calibration. In the car mode, it can directly measure the coating thickness of iron, aluminum, and zinc substrates, suitable for measuring the coating thickness of automobiles. 2. In the GM200A user mode, after calibrating the metal substrate, the user can only measure the coating thickness of this metal surface, but not other metals.For example, if you calibrate an iron substrate, you cannot measure the coating thickness of an aluminum substrate. 3. GM200A user mode calibration will not affect the car mode. 4. GM200A Car mode is the default factory setting. 5. The default factory setting of GM200A uses iron substrate to calibrate the user model. 6. According to the user model calibration, the diameter of the GM200A substrate should be ≥50mm, and the thickness of the substrate should be ≥ 0.5mm. 7. The critical thickness of GM200A to the base metal (≥ 0.5mm). 8. Edge effect: GM200A is sensitive to abrupt changes in the shape of the sample surface. Therefore, it is unreliable to measure near the edge or inner corner of the measured object. 9. GM200A can only measure non-metallic coatings.