Wire rope sling, This is a three part wire rope sling developed to give the rigger the advantages of strength combined with greater flexibility. It was created to replace large diameter single part wire rope slings which proved awkward and stiff. Tri-Flex® Slings are now manufactured in sizes from 1 ton to 145 ton capacity. Steel erectors, millwrights and riggers use Tri-Flex® slings for everything from steel erection or machinery moving to any type of heavy lift. These slings are made in matching lengths.