Headcote’s new Smart-Bit makes it easy to set screw heads with its’ special integral stop collar that is permanently mounted to the shaft of a four flute countersink. The countersink’s cobalt drill is permanently set for the correct pilot hole depth when used in 5/4" decking, and last longer than ordinary tool bits when drilling in tough decking materials. The Smart-Bit design incorporates an "O" ring on the stop collar nose which prevents spinning that could mar the deck surface. The pilot bit is a 1/8" and the countersink is 1/4". Generally, estimate one Smart-Bit for every 100-125 square feet of decking to be installed. (5/4" x 6" on 16" centers). The ball detent style bit fits standard quick change chucks. Bits are replaceable; 2 extra bits are included. Imported.