The Mitutoyo 516-935-26 gage block set includes 9 grade AS-1 steel rectangular gage blocks with nominal size engraved in inches.

Blocks included in the set measure .0625", .100", .125", .200", .250", .300", .500", 1", and 2". Grade AS-1 gage blocks are often used for calibrating and inspecting tools, instruments, and manufacturing gages.

Gage blocks (also called gauge blocks, Jo blocks, slip gauges, and Johansson gauges) are precision ground metal or ceramic blocks, used for calibrating measuring equipment and standardizing the measurement of length in manufacturing. Gauge blocks are square or rectangular in shape, with flat surfaces, and have an engraved unique identification number and length (provided in either inches or millimeters). They often come in sets with blocks of varying lengths, so that many different standard lengths can be created by stacking and wringing them. Wringing is the process of sliding blocks together with a small amount of oil, in order to create a longer surface.

The length of a gage block is usually slightly shorter than its stamped nominal length, to account for the thin layer of oil or wring film used when two or more blocks are wrung together. They are kept within a protective case, cleaned thoroughly between uses to prevent corrosion, and kept free of burrs and other damage that would decrease their accuracy. Temperature is another important consideration. Some gage blocks are vulnerable to thermal expansions and must be kept at room temperature (about 68 degrees F) to ensure their accuracy.

Gauge blocks are available in different grades, which refer to their tolerance or deviation from their nominal dimension. Grades are defined by the American National Standard for gauge blocks, the American Society of Mechanical Engineers (ASME) B89.1.9M for both length and flatness. Different grades are appropriate depending on the application and the required level of accuracy. ASME B89.1.9M also defines standards for parallelism and surface finish. A certificate of inspection and calibration is provided with each gauge block or set, specifying the deviation of the individual block from its nominal length.

Founded in Tokyo in 1934, Mitutoyo is a leader in the metrology field, producing high-quality measurement products including mechanical, dimensional gauging products, focusing on micrometers, calipers, indicators, and other measurement tools, as well as output gauges, interfaces, data collectors, and analysis software. Mitutoyo formed Mitutoyo America Corporation in 1963, which is headquartered in Aurora, Illinois, with additional locations in the U.S. and Canada.

• Product Dimensions ‏ : ‎ 9.7 x 5 x 1.9 inches; 2 Pounds
• Date First Available ‏ : ‎ November 3, 2009
• Manufacturer ‏ : ‎ Mitutoyo