Replacement parking block for FeatherCraft brand rudders. Common on a very wide range of kayak brands and models such as Boreal kayaks and the Aquaterra Sea Lion. Standard on older Hydra brand kayaks, such as the Sea Runner. Mounts onto a flat surface. Block is 2 9/16 inches long, 3/4 inch wide and stands 1 inch above the deck surface. Screw holes are 2 1/8 on center. RUDREST