Traditional round fenders tend to roll up, leaving your boat unprotected.They're also bulky to stow. Boats with step-down gunwales are especially vulnerable to damage from docks. HULL HUGR Contour Fenders stay put and stow conveniently under boat seats. They hinge to wrap around the gunwale and hull, following the contours of the boat.All HULL HUGRs are constructed of an durable marine grade tri-laminate cover, with closed cell foam inside. There's a tough polycarbonate grommet at each end for hanging from cleats.