This device is a Testex Micrometer Dial Thickness Gage, a precise instrument primarily used for measuring the roughness of blast-cleaned surfaces when used with replica tape. Usage: Specifically designed to measure surface profile according to international standards. Function: Measures the thickness of the replica tape after it has been pressed onto the surface, and the tape's backing paper thickness is subtracted to obtain the surface roughness depth. Accuracy: Features a specific clamping force and anvil/contact point dimensions to ensure accurate measurements. Reading: Displays measurements in microns or millimeters depending on the model. Would you like to know how to use it with replica tape to measure surface roughness?