The instrument consists of a completely redesigned chassis made from aerospace aluminum, which houses a high quality displacement gauge. The upper end (the shank) is the gripping area for insertion into a milling machine, drill press, or lathe. The lower end is the load cell. It extends up into the body of the hardness tester and houses a center less ground precision spring which preloads the hardened steel indenter.

The impression made by the indenter in the metal being tested is a very small hemisphere and is equivalent in size to a superficial examination in size. The resistance of the metal sample surface to the indenter results in the gauge pointer being moved to a corresponding hardness reading. Minimum sample thickness is 0.025" for most materials. If the indenter does not make a dimple on the opposite side, the material is thick enough for accurate testing.

The Model 415B is designed for use by inspection and quality control personnel, heat treaters, tool and die makers, mechanics, welders, etc. This unique instrument is the handiest and the most economical way of grading and checking various metals in equivalent Rockwell B range of 40HRB to 100HRB.