Lower hardness ref. block- 250 HBW 5/750 (actual hardness of calibration block may be differ by +/- 10 BHN) Middle hardness ref. block- 300 HBW 5/750 (actual hardness of calibration block may be differ by +/- 10 BHN) Upper hardness ref. block- 450 HBW 5/750 (actual hardness of calibration block may be differ by +/- 10 BHN)
Other size quote on request.