DEWALT D180066 4 1/8-Inch Hole Saw Double tooth design strengthens each tooth for longer life and improved durability Material application: Metal, Max RPM:85, size metric: 105 Thick, hardened backing plates prevent thread stripping and Sharper Tooth Geometry cuts material faster for faster drilling Deep cut style holes saws will cut 2x material in 1 pass. Increased high speed steel height (highest in the industry) improves hole saw durability 4-1/8" (105mm) Bi-Metal Hole Saw