BULLDOG A-Frame Mount, 7000 lbs. Designed for utility, horse/livestock, cargo, and construction trailer applications, BULLDOG Collar-Lok are the strongest in the industry. The BULLDOG design features the only automatic and continuously tight ball fit in the industry. A variety of coupler styles, tongue mounts, and latches allow configurations to match virtually any trailer. Adjustable couplers assure level operation for trailers when pulled by a variety of different vehicles.?