1 Inch Gauge Block, AS-1 Grade with Inspection Certificate. Deviation from nominal length: +10 µin. Made of steel for long lasting durability. The nominal size is printed on the front and the identification number is printed on the top. Rectangular base (Overall dimensions: 1″ x 0.35″ x 1.37″). Ideal for calibrating measuring equipment such as micrometers, sine bars, calipers, and dial indicators.