SeaKing Stores › 10mm cobalt HSS-CO jobber drill bit - EACH 10mm cobalt HSS-CO jobber drill bit - EACH £14.80 10mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO100. Add To Cart Added! 10mm diameter cobalt HSS-CO jobber drill bit. Sold individually, not as the purchase pack. Supplier reference: HSSCO100.