This Galvanized U bolt Mounting Plate has 3/8" Drilled Holes that are placed 3 inches apart. Ideally you would use this mounting plate with a U Bolt that matches those dimensions. This U Bolt Plate is commonly used on many different areas of the trailer, mostly to secure around tubing that is 3 inches wide. You can refer to the images for exact dimensions of this item. This item is very common on a Boat Trailers winch post or trailer tongue.