Master Driller #14 Self-Drilling Screw. The Master Driller is a 1/4-14 x 1-1/2" snow guard screw with a #3 point. These precision cold forged screws assure superior point strength for the fastest drill time performance through steel or nested purlins. Features a 3/8" AF Hex Washer Head. The Master Driller comes with a corrosive resistant coating to with stand all the elements. Comes with a tight sealing weather proof washer. When screwing down snow guards the use of Novaflex MR-150 is required.