A device for tightening a rod or wire rope. Its parts are a sleeve with a screwed connection at one end and a swivel at the other or, more commonly, a sleeve with screwed connections of opposite hands (left and right) at each end so that by turning the sleeve, the connected parts will be drawn together, taking up slack and producing necessary tension (see illus.). Types of ends available are hook, eye, and clevis. The turnbuckle can be connected at any convenient place in the rod or rope, and several may be used in series if required.