Blocks included in the set are 1.00, 1.25, 1.50, 2, 3, 5, 10, 15, 20, and 25 mm. Grade 0 gage blocks are often used for calibrating and inspecting tools, instruments, and manufacturing gages.

Gage blocks (also called gauge blocks, Jo blocks, Hoke blocks, and Johansson gauges) are precision ground and lapped metal or ceramic blocks, used for calibrating precision measuring equipment and as a length standard in manufacturing. Gage blocks are square or rectangular in shape, with flat and parallel measuring surfaces, and usually have an engraved unique serial number and nominal 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 pressure, in order to create a longer gage block stack.