During the quality control or maintenance of road safety guardrail or lamppost, it is essential to check their thickness and coating thickness. According to the transportation industry standards in China, the thickness of road guardrail should be 3mm or 4mm. The Zinc coating for anti corrosion should be at least 85 μm. In this case, it is recommended to use TIME2136 or TIME2430 ultrasonic thickness gauge with echo-echo mode to measure through coated surface. Meanwhile, our ferrous coating thickness gauge is suitable for inspecting the Zinc coating on guardrail.