Sealtite Kwikseal Woodbinder screws are self-drilling screws designed to attach long-life metal roofing & siding on post-frame & residential metal roof applications. Stitch screws are designed specifically to fasten overlapping panel together. Designed as an alternative to the zinc-aluminum alloy head. The smaller cupped HWH provides an attractive low-profile appearance versus larger HWH fasteners. 304 Stainless Steel cap provides lifetime warranty against red rust on the head & washer. Coated screws feature a tough 2.5 mils of powder coating that will not chalk or fade due to the UV inhibitor in all colored coatings. The combination of a sharp point & Type 17 drills 29 & 26 gauge consistently & eliminates the metal shavings that can embed themselves in the EPDM rubber washer.