Looks like an adjustable chain sling? They are sized by the chain dimensions (capacity), number or legs and length. There are a bunch of different makers.
Looks like one I have seen by Lift-all. http://www.globalindustrial.com/g/material-handling/hoists-cranes/lifting-slings-straps/adjust-a-link-chain-slings
You can buy those at fastenal. There just adjustable chains. If you have an uneven load you can lengthen or shorten the legs to balance it out. I have to have a set of those in the whatever crane I'm in. Makes it so easy to level a load. Nothing worse then trying to set something in place and one end is 5 ft higher then the other. The wll should be stamped on. I think my set is 1/2 and good for 12500 total or 6250 per leg. I can't get the link from fastenal to work.
www.grainger.com/product/LIFT-ALL-Chain-Sling-WP89128/_/N-r1xZ1z0q61l?s_pp=false&picUrl=//static.grainger.com/rp/s/is/image/Grainger/4TZK6_AS01?$smthumb$ https://www.fastenal.com/products/d...ories"|~ ~|categoryl3:"612405 Chain Slings"|~ http://www.mcmaster.com/#slings/=11ass0h
Thanks guys
You might try www.awdirect.com too. They supply the towing industry, that looks like something they would use.