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″.

Dynabrade 90875 2" Dia. Super Fine NWN DynaBrite Locking-Type Disc, 25/pack
Insize QMY-AP32-U, ROTATIONAL ABRASION TESTER, 6940561937848
3M 26140, PPS Series 2.0 Adapter, Type S45, 1/4 Female, 19 Thread BSP, 7100135336 