Surface profile gauges have a dial or digital indicator that is connected to a shaft with a contact point at the end. The contact point traces the surface of a workpiece or feature and provides a surface contour measurement. These gauges are commonly used after the surface of a workpiece has been blast-cleaned and before a finish or coating is applied. If the contours recorded are too small, the surface might be too smooth for proper adhesion; if there is significant surface roughness recorded, the workpiece could be vulnerable to rust formation because the depressions will not be coated.