All Mitutoyo gage blocks meet or exceed all known specifications. The flatness and parallelism surface finish necessary to achieve the required accuracies are the same as or better than government requirements. A certificate of inspection is furnished with all Mitutoyo gage blocks with a serial number on the case and an identification number on each block. The deviation of each block is registered. For this inspection, each gage block is measured relative to the upper level master using a gage block comparator. Grade K gage blocks are manufactured by absolute measurement using an interferometer. The gage block set and discrete gage block are supplied with a certificate of calibration. The certificate of calibration specifies the deviation from the nominal length. (Comparative measurement, however, is performed for all square gage blocks.). A certificate of accuracy, traceable to the NIST, is furnished with each Mitutoyo gage block set and individual block.