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 4124-20, PLAIN PLUG GAGE, H7, _20mm, 6928640316920
3M 78469, Cubitron II Depressed Center Grinding Wheel, T27, 4 in x 1/4 in x 3/8 in, 7100086893, 20 per case 