Depth Micrometer Masters
Depth micrometer masters are used to calibrate depth micrometers. The Depth Micrometer Master is superior to gage block calibration because they do not require block stacks so it is much faster to inspect the linear range of the tool.
https://www.threadcheck.com/depth-micrometer-masters-dm-1m-metric/surveillance-masters/
Knoop Hardness Testing
In the Knoop hardness test, a diamond pyramid indenter, which has a rhombic base with included angles of 172°30' and 130°, is pressed onto the specimen under a test force F (kgf). The hardness number (HK) is obtained by dividing the test force F by the projected area, A (mm2), of the identation. The area is calculated from the longer diagonal length, d (mm), of the indentation when the indenter is removed.
The Knoop hardness scale is generally used when shallower depth indentions are required. Knoop hardness can be measured by installing a Knoop indenter on the Macro-Vickers hard- ness testing machine.