Sub assemblies are used for chain slings (or even wire rope slings) with multiple legs. The top link is for attaching to the crane hook, and the bottom links (the smaller, sub-links) are where you connect your legs of chain. This type of setup helps you have enough room to avoid binding up, and also to keep proper lifting angles. Made from Grade 120 alloy steel, designed to be used with Grade 120 chain and fittings. Please view specs posted below to choose the proper sub-assembly for your sling. Powder-coated blue with a 4:1 safety factor.