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″.

Insize ISM-PM50, PORTABLE MEASURING MICROSCOPE, 50X, 6928640371080
3M 26129, PPS Series 2.0 Adapter, Type S34, 3/8 Female, 18 Thread NPS, 7100135938 