Features MAIN FUNCTION: Gauge block is the highest accuracy benchmark for converting broadcast wavelengths into physical length sizes. And by comparing and measuring, transfer the dimensional annotation techniques to accuracy gauges, measuring tools, and workpiec STEEL MATERIAL: Made of premium steel after heat treatment, the gauge block has the characteristics of high accuracy, low surface roughness, good bonding force, and stable size. CALIBRATION MEASUREMENT: Thickness gauge block group is ground and polished to have a very low micro surface finish; They have an accuracy of ± 0.00005in. HIGH ACCURACY: Gauge blocks have a high accuracy, low surface roughness, and good grinding force; Other accuracies used for calibrating instruments. 32PCS: There are 32 pieces gauge blocks in the box and are well identified for convenient using and storing, choose and use at will! Specification: Item Type: Gauge Block Set Material: Steel Quantity: 32 pieces Package List:32 x Gauge Block 1 x Storage Box  Package List 32 x Gauge Block 1 x Storage Box