This Standard specifies the most important design and metrological characteristics of gage blocks with a rectangular or square cross-section and a nominal length ln ranging from 0.5 mm to 1 000 mm for metric sizes and 0.010 in. to 40 in. for inch sizes. It is not the ntent of this Standard to preclude the use, by contractual agreement, of gage blocks of other shapes, grades or materials. Limit deviations and tolerances are stated for the calibration Grade K and for the Grades 00, 0, AS-1, and AS-2 for various measuring purposes. NOTE: To avoid confusing Grades 1 and 2 with previous definitions, the prefix 'AS' for 'American Standard' should be used for all sets using the grade tolerances in this Standard. NOTE: The characteristics of Grades K, 0, AS-1, and AS-2 are identical to those of the same name in ISO 3650: Gage Blocks, with the exception that in this Standard the length of the block is defined when measured in the vertical orientation. Grade 00 has been added to conform more closely to the current U.S. Standard (see section A1).