The Coolaroo turnbuckle hook can be used to stabalize and secure any Coolaroo shade sail. Simply twist the turnbuckle to increase or decrease the tension of the shade sail, ensuring that you have the perfect fit for any location. Made of durable stainless steel, allowing it to be used outdoors to withstand the elements. Can also be used in conjunction with the Coolaroo Stainless Steel Padeye-sold separately.