This hardness tester comprises the very best in "state of the art" design along with dynamic precision only found at Phase II. The 900-331 Rockwell scale hardness tester is easy to operate, yet engineered to obtain highly sensitive and accurate readings. Conforming to ASTM E-18 Rockwell Hardness standards, the 900-331 tester will offer unmatched repeatability in all standard Rockwell Hardness scales (table shown below). A perfect, rugged performer suited for any environment including heat treat facilities, tool rooms, workshops, laboratories and inspection labs. Lifetime technical support is included on all Phase II Hardness Testers. So test away with confidence and a level of accuracy you will only find at Phase II.