SeaKing Stores › 6mm cobalt HSS-CO jobber drill bit - EACH 6mm cobalt HSS-CO jobber drill bit - EACH £6.70 6mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO6. Add To Cart Added! 6mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO6.