The Turnbuckle is used with pool cover cable to secure cover.
Open the turnbuckle so that only the ends of the screw show on the inside. Pull one end of the cable through the loop of one turnbuckle screw and secure it with a cable clamp or wire rope clip (see figure below).
Pull the other end of the cable through the other loop. Pull the cable tight and secure with a second clamp. Tighten turnbuckle by turning it as shown in diagram below Make sure the cable lies on the outside of the cover all around the pool except where it goes through the pairs of grommets. The cable must fit tightly against the wall of the pool to prevent wind from getting underneath the cover. To loosen or remove cable, turn turnbuckle in the opposite direction.