The GYZJ-250 is a hard aluminium test and calibration disk used as the upper reference standard with the Barcol 934 Impressers. The GYZJ-250 is usually purchased along with the GYZJ-078 lower reference disk. Certified test disks are available to special order.
Important: Please note the GYZJ-250 used with the Barcol 934 impresser (marked '87/89') is differernt to the GYZJ-069 used with the Barcol 935 Impresser (marked '87-89'). Specifically the GYZJ-069 is softer than the GYZJ-250 and will give readings approximatly half of those marked on the disk.
