Our Turnbuckle, Stretching Screw or Bottlescrew is a Device for Adjusting the Tension or Length of Ropes, Cables, Tie Rods and other Tensioning Systems. It Normally Consists of Two Threaded Eyelets, One Screwed Into Each End of a Small Metal Loop, One with a Left-hand Thread and the other with a Right-hand Thread. the Tension Can Be Adjusted By Rotating the Loop, Which Causes Both Eyelets to Be Screwed in or Out Simultaneously, Without Twisting the Eyelets or Attached Cables.