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″.
setting ring when supplied may be .20008″.

Insize 4120-20N, METRIC THREAD RING GAGE, NO GO, M20x2.5, 6928640341823
Dynabrade 79127 3/4" W x 18" L 120 Grit DynaCut Premium Ceramic Belt, 50/pack 