This is a heavy tool formerly used by loggers to secure a load of logs onto a flatbed trailer. One would secure a pair of chains on either side of the trailer and run them to the top of the load where the load binder tool is connected to each chain end. Once clamped down, the chains are taut and off you go. With the typical rough road, they will loosen up periodically and, if one doesn’t pay attention, your load and tool will end up in the road.

Nowadays, nylon straps with ratchet ends are used.