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 4644-112, NPT THREAD PLUG GAGE, 1x11.5NPT, 6928640346866
3M 01987, General Purpose Cut-Off Wheel 3 in x 0.04 in x 3/8 in, 7100229882, 50 Per Case 