Fitted wood case and a UKAS calibration certificate. RS Pro 87 Piece Gauge Block Set. RS Pro 87 piece gauge block set, made of high-quality alloy steel with an ultra-micro-lapped surface finish heat treated and aged to give good wear resistance. Excellent inter-set wringing properties. These gauge blocks meet or exceed all known specifications. The flatness, parallelism and surface finish necessary to achieve the required accuracies are the same as or better than government requirements. Features and Benefits. High-quality alloy steel. Blocks are manufactured from specially selected high-quality age hardened alloy steel. Each gauge is marked with an identification number. Blocks are heat treated to HRC65/HV820. High resistance to wear. Chamfered edges. Each set is supplied with a UKAS 5 point Calibration Certificate. Grade 2 Workshop. Supplied in a fitted wooden case. Metric - BS EN ISO 3650: 1999. Set Configuration. 1.001 to 1.009 mm (steps of 0.001 mm). 1.01 to 1.49 mm (steps of 0.01 mm). 1.50 to 9.5 mm (steps of 0.05 mm). 10 to 100.0 mm (steps of 10 mm). Application Information. RS Pro gauge block sets are used by engineers and machine shops to measure in microns and to calibrate other measuring tool.