Trailer Leaf Spring Shackle Bolts 9/16" -18 X 3-1/2" long with Lock Nuts, Set of 4 -23011/23012 9/16"-18 x 3-1/2" trailer leaf spring shackle bolts and locknuts for mounting slipper spring onto hanger bracket or equalizer, Diameter: 9/16";Threads per inch: 18;Length: 3-1/2",Grade: 5 9/16-18 lock nuts Mostly used on mounting 2" wide slipper or double eye leaf springs onto hanger bracket or equalizers 4 bolts and 4 nuts