Rockwell indenters have been in service for decades and are recognized for their reliability, ease of use and broad deployment in the hardness testing field. The 3R model is equipped with 1/16 inch tungsten carbide ball diameter and operates on Rockwell Scale B. The 4JR model operates on Rockwell C scale and uses diamond brale indenter. To assure measurement accuracy, the periodic equipment calibration can be done in the lab with the existing hardness test blocks.