Sealey hss drill bit set 1 10mm 170 pieces sealey dbs170cb this 170 piece hss cobalt drill bit set from sealey features fully ground hss bits manufactured to din 338 the 5 cobalt gives increased heat hardness which helps extend the life of the drill bit while the 135deg split point is self centring and helps to reduce thrust and aids an easier penetration efficient clog free swarf clearance drills can be re sharpened without affecting their performance sealey dbs170cb hss cobalt dri