If you're looking for a smoother ride for your vehicle that has a coil spring suspension, Firestone Coil-Rite air helper springs are what you need. Designed to fit inside existing coil springs to create a variable spring rate, Coil-Rite will level your vehicle and assist with more effective braking and handling, even under heavy loading and adverse road conditions.Coil-Rite enables you to control the air pressure in the air helper springs so you can make adjustments for varying loads and road conditions. Spring performance can be altered as easily as inflating a tire.Firestone Coil-Rite air helper springs are made of durable, elastic polyurethane, providing years of comfort and stability to your vehicle. The air springs will support 500-1000 lbs. per set (not to exceed vehicle's GVWR). Coil-Rite Air Helper Springs are designed to work in temperatures between 180 Â°F (82 Â°C) and -40 Â°F (-40 Â°C).