M8 J Hook Bolts are designed to create a waterproof seal between two single corrugated sheets when best practice is followed. Roofing hook bolts are designed for fastening single corrugated sheeting to angle or channel roof steel beams. Sold in box of 50 and supplied with square bolts, the Roofing M8 Hook Bolts are manufactured out of a single piece of zinc and yellow coated to prevent the build-up of rust.