1).High Quality➯Marine grade 316 stainless steel.Supper corrosion and strong endurance, durable in all conditions. 2).Sturdy Construction➯Solid 1/2 inch Shaft,durable and long-lasting,Build to resist daily scratches, corrosion and tarnish. 3).U cup design➯Opening design gives more convenience,make it easy to operate, simple, and good practical. 4).Dimension➯ Length:5-1/6 inch(131mm);Shaft Length:2-1/8 inch(54mm);Shaft diameter:1/2 inch(12.5mm);Fits Oars diameter from (46mm-56mm) 5).Pre-drilled pin holes➯Easy to install,suit for small boats,canoe,kayak,dinghy, lifeboat, water raft boat.etc. 6).If you have any questions about our products, please let us know and we are glad to serve you. 316 Marine Stainless Steel,highly-polished,stronger anti-rust,can be used in highly corrosive marine environments. The Clamp-On Oarlock fastens securely to the oar with one adjustable bolt with no drilling required. Shaft Diameter: 1/2 inch /12.8 mm.Pre-drilled pin holes. Easy to install,suit for small boats,canoe,kayak,dinghy, lifeboat, water raft boat.etc.