SeaKing Stores › 8mm cobalt HSS-CO jobber drill bit - EACH 8mm cobalt HSS-CO jobber drill bit - EACH £10.30 8mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO8. Add To Cart Added! 8mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO8.