Diablo, 5 Pack, 3-1/4 HVAC Rec Blade, Diablo's New 3-1/4" 32 TPI HVAC/Ductwork Bi-Metal Reciprocating Saw Blades Are Specifically Designed For The Trades To Deliver Maximum Performance In Thin Metal Cutting Applications. An Ultra-Hardened Cutting Edge Delivers Up To 5X Longer Life Than Those Of Standard Blades. The Compact Blade Body And Fast Puncture Tip Design Allow Users To Easily Engage In The Material Without Additional Tools. A Higher Tooth Count Configuration And Small Gullets Enables The Blades To Quickly Slice Through Thin Metals With Ease While Limiting Excessive Vibration. Perma-SHIELD Non-Stick Coating Prevents Gumming And Friction In Metal Cutting.