The depth micrometer masters - models ADM are available in both inches and millimeters.
The inch range is .500" ‐ 5.500" in 1.00" steps +/‐ .0001". An ADM Riser can be added to increase the range from .500" to 11.50" in 1.00" steps +/‐.0002"
The metric range is 12.5 to 137.5mm in 25.0mm steps +/- .0025mm. An ADM Riser can be added to increase the range from 12.5mm to 287.5mm in 25.0mm steps +/- .005mm.
The depth micrometer masters are case hardened, stabilized, ground and lapped. Depth micrometer masters are used to calibrate depth micrometers. The depth micrometer master is superior to Gage Blocks calibration because they eliminate the requirement to stack gage blocks. Using the masters is faster and more efficient for inspecting the linear range of the tool.