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″.

Dynabrade 78320 3" Dia. x 1" W x 1/4" Shank, Medium, NWN DynaBrite Wheel, 10/pack
Insize ISY-100-4001, HORIZONTAL SPRING STAND, 2PCS, 6940561936155
3M 01988, General Purpose Cut-Off Wheel 3 in x 1/16 in x 3/8 in, 7100229881, 50 Per Case 