IVY Classic 28068 4-1/4-Inch Bi-Metal Variable Pitch Hole Saw, 1/Box Cuts stainless and mild steel, non-ferrous metal, plastic and wood, Cobalt Advantedge (Registered Trademark) Bi-Metal construction with M-3 cutting edge retains hardness Variable pitch, positive rake tooth design 4-6 TPI minimizes tooth wear Thick backing plate prevents thread stripping and increases torque 1-1/2" cutting depth cuts through 2 x 4s in one pass