This tool is used in industry to determine the Hardness of a material according to the Mohs scale. The kit contains 8 different Mohs' Hardness Points, from Mohs 2 through Mohs 9. These points are used in a "scratch test" on the material. For example, if the number 6 point scratches a particular material, but the number 5 point does not, then your material has a Mohs' Hardness value of about 5.5. A common use of this tool is in Concrete Hardness Testing to guide the technician in selecting the optimal abrasive to use in the concrete polishing.
Mohs' Hardness Kit