SeaKing Stores › 5mm cobalt HSS-CO jobber drill bit - EACH 5mm cobalt HSS-CO jobber drill bit - EACH £5.30 5mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO5. Add To Cart Added! 5mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO5.