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 3290-347, V-ANVIL MICROMETER_7 flutes_2.6-3.4", 6928640377990
3M 26120, PPS Series 2.0 Adapter, Type S28, 17.5 mm Female, 19 TPI
Thread, 7100135956 