Starrett blocks can be used to test Brinell or Vickers scales. They are available in steel, brass and aluminum. Each block is serialized, with a certificate detailing the environmental conditions used to test the block. Actual readings are given, with the averages of these readings: min. reading, max reading and a repeatability figure. The blocks are calibrated according to ASTM E-18 standards, ANSI (NCSL) Z540-1, (ISO) 10012-1, ISO/IEC 17025 and Mil-std 45662A. Min Brinell Block 187 1/2kg, 2 1/2mm Ball Mil-std 45662A. For use with Starrett Bench Top Hardness Testers 2-1/2mm Made in United States