Links: Technical Specification | Data Sheet 

This simple gauge has been designed to provide inspectors with a low cost alternative to a graduated microscope for determining the width of a crack in concrete or other building materials.

Similar in size to a standard credit card, this transparent gauge is marked with a range of graded lines. Each line is a specified width.

To use, position the gauge over the crack and identify which line is a similar width to the crack. Read off the width value.