These kind of chain link connectors are very useful when I'm rigging up systems to hang my chandeliers so I have a little collection of them.
Yesterday I took some friends to a place known as Bogey Knights in a tucked away corner of Plymouth next to the dockyard. It sells army and navy surplus stuff and chandlery, so if you're looking for an old anchor....this is your place.
Here we marvelled at the huge accessories, I stuck my very cold fingers into the photo to show you the scale. This is exactly the same design as the little one in the top picture - but surely I would need huge arms and hands 10 times bigger to screw these securely!
I love this huge pulley part, it looks like a pantomime prop! I've used the domestic size for putting my candle only chandeliers on a pulley (no electrical wiring to disturb) with this part guiding the cord, but this one looks like it would pull your ceiling down. So - respect to all those deck crews who actually handle all this enormous stuff.