CE Smith Trailer 10205GA Swivel Bracket (Pair)- Replacement Parts and Accessories for Your Ski Boat, Fishing Boat or Sailboat Trailer Bunk Flange holes 3/8 inch dia Bunk Flange 1-3/8" x 3-1/2" Swivel Flange hole 1/2 inch dia Swivel Flange 2" tall x 3-1/2" 2-1/2 inch bunk Flange hole centers & 1 hole centered