A link such as a karabiner has a body portion and a gate portion which is mounted to the body portion about a pivot. The gate defines a free end which is arranged to inter-engage with a nose of the body portion to define a closed ring for receiving a rope passing therethrough and including a first sleeve which, when the ring is closed, is moveable between a first position where the gate is free to rotate about the pivot in at least one direction, and a second position where the sleeve at least partly encloses the free end of the gate and the nose and substantially prevents rotation of the gate about the pivot. The link further includes a second sleeve which is internally threaded and which is mounted on an externally threaded portion of the gate for movement towards and away from the free end of the gate and which may be rotated towards the first sleeve when the first sleeve is in the second position, to prevent movement of the sleeve into first position in which the gate is free to rotate. A dual sleeve maillon, of similar design but omitting the pivoting gate having two sleeves is also described.