Heavy Duty Large Double Convoluted Replacement Air Spring. Use Pacbrake's heavy duty air springs to eliminate your vehicle's sag, sway and bottoming out. Distribute weight evenly to your tires supporting any load without overtaxing your suspension. Pacbrake air bags are the Only heavy duty air bags on the market with one piece aluminum end caps and 20 support wires giving you maximum strength and durability! The number one solution to level your truck's stance while providing added support for an overall smoother, safer ride.