Sea-Dog Steel 90 Concave Base Deck Hinge Stainless. Concave Hinges are designed to rail mount on 7/8 tubing. Angled Hinges are used for mounting items on slanted surfaces like sloped gunwales. 3/16 pin size. Constructed of UV stabilized injection molded nylon. Installs with two #10 FH fasteners (not included). Available in black or white. Specifications for Sea-Dog Stainless Steel 90 Concave Base Deck Hinge: Manufacturer: Sea-Dog Color: Silver Package Contents: Sea-Dog Stainless Steel 90 Concave Base Deck Hinge Sea-Dog 270240-1: Steel 90 Concave Base Deck Hinge Stainless