IRWIN 3 8 in 12 Step Drill Bit Flooring Samples Used where the chimney passes and steel yoke housing Used where the chimney passes through a roof with a pitch of flat to 6 12 Comes complete with storm collar Used to seal the opening where the chimney penetrates the roof Lifetime limited warranty contents will vary based on size and model 12 hole sizes M35 grade cobalt HSS High heat and abrasion resistance Longest cutting edge life Single fluted cutting edge for greater control and rounder holes Ideal for drilling holes in thin materials such as mild steel wood and laminates 3 flatted shank won't slip in chuck SpeedPoint tip for fast starting Laser marked sizes won't wear off with use