"MIDWEST" COMBO TAPPING SCREW For exterior use of all types including decks and fences.Rust resistant but not rust proof. Zinc dichromate coating. Diamond point provides self-threading, maximum holding power for fastening conduit clips, furring strips, junction boxes, expansion joints, wall partitions/insulation, stud track, window/door frames, duct strap, gutters, joist hangers, shelves, signs and cabinetsBoxed 100 12 no Diameter 3/4" Length Zinc plated Pan head - Phillips