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 ISY-100-27026, SUPPORT HEAD, aluminum, 6928640393846
3M 06460, Cut & Grind Wheel, Type 27, 4 in x 1/8 in x 3/8 in, 7100213972, 20 per case 