Firestone's Coil-Rite air helper springs mount inside the coils of an existing coil-spring suspension to give your vehicle a boost when it needs it the most. They're constructed from durable polyurethane and allow for adjustable spring rates that are far superior to those of standard coil springs. Installing them will allow your suspension to support an additional 500 to 1,000 lbs. per set. Installation does not require drilling on the Coil-Rite models.