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. Available in both old style (S-319A) and new style (S-319AN) styles, be sure to note the type of latch kit that will work with any given hook below (click the PDF at right for full product specifications and instructions). Frame sizes "O" and larger are old style only, and most of these larger sizes offer a standard length or an extended length shank--see chart below. Forged from alloy steel, Quenched and Tempered. Each hook bears an identification code for full product traceability. Made in the U.S.A.