A turnbuckle is a mechanical tensioning device used to adjust and maintain the tension or length of ropes, wire ropes, cables, chains, and tie rods. It consists of a central body with threaded openings at both ends, fitted with two threaded end fittings—such as eye, hook, or jaw ends. By rotating the body, the turnbuckle either tightens or loosens the connected assembly without removing the end fittings.