These special thimbles are designed to keep the right size of shackle with the right sling. You've seen it before. A wire rope bridle sling goes out to the field with the right shackles, the right rating, etc. But somebody needs a shackle, so they borrow one off the sling. When the shackle(s) is finally replaced, it may or may not be the same one, the same size, the same rating. This is dangerous because your once certified lifting sling may now be unsafe to use. These thimbles have a welded tab on the inside that keeps the shackle from being removed (without a lot of extra work). Other than that, they perform just like other thimbles and offer the same benefits like extended life of your wire rope eyes and overall sling life. Made with a hot-dip galvanized finish.