A turnbuckle is a device for adjusting the tension or length of ropes, cables, tie rods, and other tensioning systems. It consists of two threaded bolts, one screwed into each end of a galvanised steel frame, one with a left-hand thread and the other with a right-hand thread. The tension can be adjusted by rotating the frame, which causes both bolts to be screwed in or out simultaneously, without twisting the eye/hook bolts or attached cables.