For zero setting of inside micrometers, three points internal micrometers and bore gages.
Deviation is the difference between the ordered size and the size marked on the setting ring when supplied.
For example, the ordered size is .2”, the size marked on the setting ring when supplied may be .20008″.

3M 72359, PELTOR Hygiene Kit for Earmuffs HYX4/37283(AAD), Hearing Conservation, 10 Kits/Case, 7000104048
Dynabrade 51106 Collet, 5/16"-24 Female Thread, 1/4" Capacity, 4-Piece Collet 