ProFit 1015 1177 Constant Pitch Bi-Metal PLUS Hole Saw, 6 31/32-Inch, Yellow Constant Pitch makes this hole saw ideal for cutting through thin sheet metal, up to 1/8" thickness 8% Cobalt in the teeth to make the hole saw last longer Hole saw cutting depth of 1 1/2" Quick Lock system - Change between hole saw sizes and styles in seconds, enlarge an existing hole Bi-Metal - Only Accessory needed is the QLH1 or the QLH2. Cannot use this hole saw without on of these Quick Lock center drills The need for a common arbor is eliminated. This system only requires the use of a ProFit center drill. Center drill QLH1 for sizes 9/16" to 1 3/16" or QLH2 for sizes 1 1/4" and up