Unlike traditional boat fenders, the contoured shape prevents these boat dock fenders from rolling or riding up, meaning your boat stays protected. These boat fender attachments hinge to wrap around the gunwale and hull, following the contours of the boat. All Hull Hugr products are constructed with a marine-grade, rip-proof, tri-laminate cover, with closed cell foam inside. Durable polycarbonate grommets at each end allow you to hang them from cleats.