CE Smith 15274A Zinc Plated U-Bolt; Square; 1/2" Diameter; Thread 13; W 3-1/8" x L 4-1/4"- Replacement Parts and Accessories for Your Ski Boat, Fishing Boat or Sailboat Trailer Square bend This item is rated grade five 1/2 inch -13 diameter thread 3-1/8" w x 4-1/4" L