The gauges consist of two overlapping plates. The bottom plate is calibrated in millimeters, while the top transparent plate has a hairline cursor in the form of a . This design enables accurate monitoring of cracks. Made from polymer, the monitors are waterproof, sunlight , wear-, and scratch-. The highly transparent plastic sheet provides a clear and precise measurement grid. The monitors come with a redesigned fixing column that easily connects the two pieces without the need for glue. This ensures a secure and hassle-free installation. These monitors are specially designed to monitor cracks in walls and track their evolution over time. Keep track of wall deformation and changes with the included monitoring sheet., Weight: 0.10802650838 pounds, Manufacturer: susaa