SnoBlox Deuce can be mounted with adhesive or screws. Screw hole placement is optimized to attach to the roof purlins. Fits most popular 36" metal panels with three 12" flats or four 9" flats without rib straddling! Starter points are provided for mechanical fastening. Come with two-inch long quarter-inch thick, self-starting screws with rubber washers. ATI lab tests show 3,456lbs strength with mechanical attachment. Two screw holes are strategically placed across from each other, near the face of the snow guard for wood structures or purlins. SnoBlox polycarbonate plastic snow guards are manufactured from virgin grade, UV-stable, polycarbonate. From the originators of the polycarbonate snow guard, our products have helped prevent damage from snow and ice avalanches on sloped metal roofs since 1976. This kit is designed for screw-down metal roofs that are attached to wood purlins. Kit Includes 25 Clear SnoBlox Deuce Snow Stops, 1 tube of NovaFlex Neutral Cure Clear Sealant, and 50 self-tapping #14 screws with an attached neoprene washer that measure 2 inches long. Verify the thickness of the insulation under the panel, if any, to ensure the provided 2-inch screws fully engage in the purlin. The Sealant is safe for use on Kynar and Galvalume panels with a service Temp of -40F – 400F. Application temperature is between 0F – 120F. Instructions for installation can be seen in pictures. Placement of snow guards in isolated areas such as chimneys, doorways, vents, and partial roof sections is NOT recommended.