Hardness Test File Set
Start with Black handle file (65HRC) and run the file over the material, If the file marks the material is soft than the file.
Repeat the procedure with the next Yellow (60HRC) and continue the procedure until a file does not mark the material. The material hardness is then between the hardness of the two files will and will not mark the material.
6pcs/set: Purple Handle (HRC40), Green Handle (HRC45), Blue Handle (HRC50), Red Handle (HRC55), Yellow Handle (HRC60), Black Handle (HRC65)