Buyers Products (0091558 2-5/16" Heavy Duty Cast Coupler with 4-Hole Mounting Plate Easy one-hand latch operation Keep latch conveniently pinned open while uncoupling the trailer Tough, sturdy cast steel construction 4-1/2 In. square hole pattern to suit 5/8 In. bolts Maximum Gross Trailer Weight of 18,000 lbs.