81 pc Grade B Steel Gage Block Set with MFG'S certificate Manufactured under carefully controlled conditions allowing for the highest degrees of accuracy when used at a temperature of 68 degrees F. (20 C). All gage block sets are assigned serial numbers and accompanied with a certificate of inspection listing the deviation for each block Each gage block set meets or exceeds federal specification ASME B89.1.9-2002. Hardened to HRC 64 / All gage block sets are made to special standard to resist corrosion and defacement The Accusize Industrial Tools Steel Gauge Block Set is essential for precision measurement in industrial settings. This 81-piece set, conforming to Grade B standards, is meticulously manufactured for reliability and accuracy. Each block is calibrated under controlled conditions, ensuring accurate measurements at a standard 20°C (68°F). The set includes a manufacturer's certificate, detailing the deviation of each block, guaranteeing its precision. With each block serialized for traceability and meeting the stringent ASME B89.1.9-2002 specifications, you are assured of a product that meets and exceeds industry expectations. The blocks are hardened to HRC 64, providing exceptional durability and resistance to corrosion. It is ideal for professionals demanding the highest degree of measurement accuracy.