1/4-20 x 3 1/2 Phillips Flat with Wings Self Drill Screw WAR Coated

1/4-20 x 3 1/2 Phillips Flat with Wings Self Drill Screw WAR Coated . Phillips flat head tapping screw , spaced or unified threads, and a #3 or #4 drill point. Designed to drill through steel to attach wood to metal. AISI 1022 or equivalent steel. Rockwell C50-56. Meets F.I.P.-1000.7 for torsional strength & drill speed. Meets ASTM A 510 for carbon steel manufacturing. Exceeds 1,000/hr. salt spray resistance. Designed to work with ACQ treated lumber. Highly corrosion resistant.