The H Shackle can be used on grommet seats, tire swing sets, and many other uses. Requires an Allen Wrench with Special Head to tighten and loosen. Using the H Shackle is an easy decision as it meets all safety standards when properly installed onto a commercial grade swing set. Some swing hangers come with shackles built on, which offers an even easier installation than standard S-Hooks. Purchase an H Shackle along with any other swing accessories from AAA State of Play and receive advice from any of our skilled and trained customer service reps.