Sets of gage blocks come with a corresponding grade. The grades of gage blocks representing the tightness of tolerance on their respective sizes. The higher the grade of a gage blocks, the higher level of tightness of its tolerance, and therefore the higher degree of accuracy and precision it is capable of accomplishing. Grade tolerance comes in 0.5, 1, 2, or 3. The gage blocks of a higher grade, 0.5 and 1, are most often used as calibration tools, also known as calibration masters. Those with a lower grade, 2 and 3, are used for either gauging or for measurement. Back to entire glossary