Aluminum Swivel Ring Rope Tie Down Horse Trailer 1-7/8″ These are Aluminum Bolt on Swivel Loop style D Rings. I use these D rings on my Flat bed trailers and horse trailers trailers. You can use them for that, or install them in your Horse Barn, Bed Room, Boat Dock, Boat, Work Shop, Your 4wd truck or ATV, or just about anywhere you want to tie something up or chain something down! It is 100% Aluminum, no rust, ever. USA made Quality, Buffed smooth, no rough edges! Dimensions: Now, for the details. The actual Circle ring on this Aluminum tie down loop is 7/16″ (just under 1/2″) thick, and measures 1-7/8″ Inside x 2 3/4″ Outside Diameter dimensions. The “foot print” of the bracket is 1″ wide, and 3 5/8″ long. It is 3/8″ thick at the bolt holes and 1″ tall overall Hole size is 3/8″ Holes are spaced 2-5/8″ inches center to center.