Sealtite ZXL Steelbinder screws are self-drilling pole barn screws designed to attach long-life metal roof and sidewall panels such as Galvalume on pre-engineered metal buildings. 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. 5/16" Cupped HWH ZAMAC 5 Zinc-Aluminum Alloy provides lifetime protection against red rust on the head. The ZAMAC 5 alloy provides more strength than the more common ZAMAC 3. You may obtain a free copy of the written warranty from Sealtite upon request. Washer face design helps to capture rubber EPDM washer even when driven at an angle. #12 & 1/4" diameter drill point easily penetrates steel thickness up to .210" with no “point walking”.