Pro Comp is the fastest, safest, least expensive way to bring the front of your Toyota Tundra Double Cab level with the rear. This gives you the clearance and ability to add wheels and tires up to 33" in diameter. Pro Comp products do not affect the factory OEM ride quality or comfort. Pro Comp Strut Extensions, unlike urethane strut spacers, never wear out, never need to be re-torqued, and do not affect the OEM-quality ride. Pro Comp Strut Extensions are made from plate steel over .25 inch thick. They mount on top of the strut assembly, eliminating the hassle, time and danger of compressing springs. Thats why Pro Comp also offers a lifetime warranty for as long as you own your vehicle against defects for all of our products.