Shank hooks are designed to be threaded by the end user after purchase. They are most commonly installed into crane blocks, which is why Crosby's wide selection of shank hooks has helped to make them an industry leader--you're sure to find a shank hook that can be threaded to meet your needs. Sizes 1T - 22T feature Crosby's S-4320 latch (installed), which meets the world standard for lifting. It's a heavy-duty stamped latch that interlocks with the hook tip and features a high cycle, long life spring. Larger sizes utilize the "Old Style" SS-4055 Latch Kit, or the Heavy-Duty PL Latch Kit (sold separately). Hooks are made from forged from alloy steel, Quenched and Tempered. Each hook bears an identification code for full product traceability. Made in the U.S.A.