Century Drill and Tool 5910 Shark Tooth Bi-Metal Hole Saw Metal Door Lock Installation Kit, 4 Piece 3 quick easy steps for quick door installation for metal doors 1-3/8-Inch or 1-3/4-inch back sets 2-3/8-Inch or 2-3/4-Inch Professional bi-metal hole saws with cobalt high speed steel teeth electron welded to shatterproof shock absorbing alloy bodies Cuts up to 1-1/2-Inch deep holes Can be used in portable electric drill machines lathes and milling machines Made in the USA