mk4c, mainly used as small buttons for percussion bits to cut soft and medium hard formations;
Mk6, for coring crowns, electric coal drill bits, coal cutting picks, oil cone bits and scraing knife bits, used in gelolgical prospecting , coal mining and oil well boring;
Mk8,
MK05, MK8C, MYK15,MYK20,MYK25,MK11C ...............