Carlisle (aka Old Town) Clamp-On Oar Locks are used to secure rowing oars to your canoe that MUST already be outfitted with Oar Lock Sockets. Best used with Carlisle aluminum Economy boat oars. Molded of stainless steel-reinforced super tough black synthetic plastic, rustproof, rattle and squeak free. Sleeves Not Included! Fits 5/8 inch sockets. Sold in pairs. Carlisle Old Town part number 01.2510.0000.