Rubert - Surface Comparator is specially designed to check the roughness of steel surfaces that have been blast cleaned to cleanliness grades SA 2.5 and SA 3 in preparation for painting. This Surface Comparator can be used for checking roughness of turned, milled, ground, reamed, polished or lapped parts during machining. Along with that, this Surface Comparator conforms to ISO 8503. These products are easy to use, place the surface roughness comparator against an area of the test surface, and compare in turn the four sectors of the comparator against the test surface using the X7 magnifier, placed so that the test surface is viewed. When steel has been blast cleaned, the surface consists of random irregularities with peaks and valleys that are not easily characterized. Experts have recommended that the profile be identified as dimpled (shot blast) or angular (grit blast) and be graded. Product Specifications Brand: Rubert Product: Surface Comparator