Shackle straps are among the trailer parts that break most frequently, so it might be a good idea for you to invest in this pack of 4 Uriah Products shackle straps. Having some on hand allows you to monitor your existing straps and replace them at the first sign of wear in order to avoid having one break on you when you're on the road. These have a 9/16" bolt hole diameter. | Uriah Shackle Strap 4 Pack | Size 2-1/4"