Shackle strap bolts are among the trailer parts that break the most due to the high amounts of wear and tear they face. This means that it's a good idea to keep some extras on hand, such as the 4 included in this set from Uriah Products. That allows you to replace your existing strap bolts at the first sign of wear. These bolts are 3" long with a 9/16" diameter. | Uriah Shackle Bolt for 1 3/4" Spring