These shackles are designed with an increased bow radius and oversized pin, because a wider bearing surface promotes longer sling life. They feature an all alloy construction for durability, and each shackle is traceable with a PIC code. Using such a shackle means you retain the full strength of your sling (be sure to use the right size shackle to pair with your sling's rating). Safety factor of 5:1. These shackles are ASME B30.26 compliant. Crosby also makes some very handy accessories to use with these shackles, including the S-255 Spool and S-256 Link Plate, which are designed specifically to help you properly use these shackles, maintaining proper connections and sling contact.