Turn-buckle
Turn-buckle (tûrn"buk`k'l) , noun
(a)
(Mechanics) A loop or sleeve with a screw thread at one end and a swivel at the other, -- used for tightening a rod, stay, etc.
(b)
(Mechanics) A gravitating catch, as for fastening a shutter, the end of a chain, or a hasp.