David Ellis Co., inc. is a leader in the manufacture of metal hardness blocks, combining 125 years of experience in the maintenance, calibration and service of various types of durometers to produce all scale sizes of cloth, rockwell, Knoll and vickers blocks. David Ellis Co., inc. has passed NAVLP's ISO/IEC 17025:2005 laboratory certification, and all the hardness blocks meet the requirements of ASTM standard, international ISO standard and military standard, etc. They can be traced to NIST national metrology institute in the United States, and are now sold from stock.

The ASTM e-10 Brinell hardness block subject to the original loading and subject to an authoritative test report shall be traceable to NIST national institute of measurement