Our set of surface roughness standards contains 30 samples of 7/8" x 3/8" electroformed solid nickel plates for quickly evaluating the surface finish for six of the most common machining methods. Markings for each of the lapping, reaming, grinding, milling, and turning standards are in AA (micro-inches) and the metric equivalent, Ra (micrometers). Each surface type is consistently reproduced from masters and is accurate within ±10% of the nominal value. An ideal tool for quality assurance labs, engineering departments, drafting rooms, and machine shops, the standard gives the designer or operator a realistic idea of the feel, appearance, and texture of machined components. Instructions and CLA/Ra/AA correlation graph is included. The standard is packaged in a handy 6" x 3" wallet carrying case. Calibrated unit includes long form NIST traceable calibration report.