Hook to hook turnbuckle 10mm made of heavy duty galvanised steel. The hook-to-hook adjuster will adjust from 254mm to 342mm. Turnbuckles or straining/rigging screws are commonly used to properly tension cables, ropes and rigging systems on boats, such as mast and sail rigging, safety lines, as well as various other deck hardware. Inside hook: 14mm, body length: 133mm.