The CURT Flex Air 5th Wheel Pin Box is designed to regulate and reduce movement during towing, giving you a relaxed feel as you hit the road with your trailer or RV. The Flex Air features an internal air bag and built-in strut that team up with a rubberized pivoting head to reduce chucking and virtually eliminate bounce and jarring. The pivoting head regulates movement of the king pin within the hitch while the rubber compound absorbs road shock, giving you a smooth ride that keeps things in control through harsh roads. This internal air bag moves in a scissor-like motion to absorb vibrations. The Flex Air also utilizes a rubberized compound to soften jarring movement and an oil shock absorber to handle rebound action, dampen kickback, and control chucking. The Flex Air 5th Wheel Pin Box combines time-tested Air Ride technology with Rota-Flex pivoting head to significantly reduce fore to aft movement and vertical tug-of-war between a 5th wheel RV and tow vehicle. Towing 18, 000 lbs. never felt so good. The Flex Air is designed to replace Lippert 1621 pin boxes and has an 18, 000-lb. gross trailer weight (GTW). It comes ready to install and uses the same bolts as the original pin box, so it doesn't require any additional hardware for installation. Constructed with high-strength steel and finished with a black powder coating, the Flex Air is the ultimate 5th wheel pin box to tackle your towing needs for the road ahead.• Replaces Lippert 1621 5th wheel pin boxes• Reduces chucking and absorbs road shock• Long jaw with pivoting head• Air Ride technology• Bolt-on installation with no assembly required• Constructed with steel and a black powder coat finish that protects against rust• 18, 000-lb. towing capacity Oil shock absorber handles rebound action & dampens kickback Rota-Flex pivoting head reduces fore to aft movement & vertical tug of war 18, 000-lb. gross trailer weight (GTW) | Curt L05 Flex Air Pin Box, 18,000 lbs in Black