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 Nitro Series MNF13 Mini-Nitrofile Abrasive Belt Tool
3M 16579, Accuspray ONE Replacement Spray Gun, 7100096183
Dynabrade 11477 Dynabelter Abrasive Belt Tool, Heavy-Duty 
