I was working recently on an antenna and a visitor was intrigued by a device I was using.
Above, the device is for tensioning a wire span, commonly called a come-along though that term gets applied to all manner for appliances for broadly similar purpose. A significant difference is that this was designed for smooth hard drawn copper wires, and has smooth flat jaws (70x6mm) and does not put a kink in the wire (as do most wire grips for more general fencing and FSWR use). This one has had the strap replaced, it came with a 1.25″ canvas reinforced rubber transmission belt which became hard over time.
I purchased this one from a manufacturer in Adelaide in 1980, one of a few left overs from a production run for the then Telecom Australia where they were used for aerial telephone wires.
I came across them in OTC where the riggers used them for HF wire rhombics and the associated transmission lines, and when I moved to Canberra in 1980 I dug out the engineering drawings for them, and contacted the manufacturer.