This is the best weight distributing hitch you can buy. We used it on a 35' Travel trailer but recently purchased a motor home. The Husky Center Line Head Assembly Kit includes head assembly, spring bar brackets, hardware kit and 10 inches shank. This product includes the spring bars that are required to complete hitch. The Center Line Torsion Weight Distribution Hitch and Active Sway Control System is the next generation in towing safety and performance. This sway control system provides you with complete confidence during your towing experience. Compression cylinder action and torsion spring bars work together to distribute weight and oppose trailer sway before it begins, keeping your trailer straight and on center, giving you increased control. The Center Line system can be used in all driving and weather conditions including backing-up. The easy adjust head alignment systems allow quick and easy set-up at the time of installation. Advantages of Husky's Center Line active sway control technology: compression cylinder design applies counter pressure to actively control trailer sway; eliminates use of clamped friction materials; provides constant pressure to re-center the trailer behind the tow vehicle; can be used while backing up; tapered torsion spring bars help transfer weight between all axles of the two vehicles for safe towing. Head assembly kit has tongue weight range 500 to 1,400 pounds and gross trailer weight 4,000 to 14,000 pounds. The additional Husky 31512 Center Line Spring Bars - (801 lb. to 1200 lb. Tongue Weight Capacity) are included.