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 01049 Air Motor
Dynabrade 14230 Rubber Drive Wheel
Dynabrade 78479 3" Dia. x 1", 1/4-20 Female Center Thread, A/O, 120 Grit, 8-Ply J-DynaCut Cross Pad, 100/pack
Dynabrade 69453 Drop-In Motor 