Sealey hss cobalt drill bits fully ground 1 13mm sealey db105cb this drill bit from sealey is a fully ground hss cobalt drill bit manufactured to din 338 the 5 cobalt gives increased heat hardness which helps extend the life of the drill bit while the 135 split point is self centring helping to reduce thrust and aids an easier penetration another feature is the efficient clog free swarf clearance while the bit can be re sharpened without affecting its performance sealey db105cb hss