Bosch Hole Saw HBT450 4 1 2 Inch Bi Metal M42 Cobalt Progressor Tooth Cutter (5 TPI Geometry Wood Stainless Metal Ventilation Conduit Boring Tool) Double Flute Straight Bit Advanced Seal Protection: Features a Advanced Seal Protection: Features a single mechanical seal with a silicon carbide face for superior abrasion resistance (28) 3 8" Drive 6 Point Standard Sockets (SAE: 1 4" to 7 8" Metric: 6mm to 22mm) and catastrophic teeth fragmentation under continuous load conditions by combining an active 5 TPI Progressor tooth geometry with integrated side wall triangle ejection slots and a reinforced torque dampening base shoulder extending active tool life parameters over standard carbon steel configurations