Large Frame U-Bolt Kit U-bolts for mounting to frames up to 3" wide x 5-1/4" high; Leg length is 6" with a thread length of 2"; 4 U-Bolts per kit.(nuts and washers not included); For use with our Roller Guide-Ons, Post Guide-Ons and Bunkboard Guide-Ons; Genuine replacement part for C.E. Smith Part Numbers 27600, 27610, 27620, 27625, 27640, 27645, 27660; 5' Bunk board style guide-ons (P/N 27600)require (2) kits, all other guide-ons require (1) kit;