Crack monitoring tell-tale crack monitors. A straightforward and practical analog crack monitoring device. Features ±1 mm (± 0.04" ) tick marks on X-Y axes with ± 0.5 mm (± 0.02" ) discrimination. Provides a ±20 mm (± 0.79" ) horizontal range and a ±10 mm (± 0.38" ) vertical range. Made from high-quality polymer with a clear and easy-to-read measurement grid. The crack monitoring scale is utilized to monitor cracks in walls and track their progression over time