Patented SumoSprings offer enhanced suspension stabilization for trucks, vans and RVs using microcellular urethane springs that provide a smooth, progressive spring rate. They work in conjunction with original equipment to share the load, helping level out sag and reduce wear and tear on your suspension. SumoSprings provide additional load support, reduce sway and deliver a smoother ride. Secured top and bottom with steel mounting brackets and hardware, they are maintenance free, dont leak air and require no air lines or compressors. Available in sizes and densities to support multiple front and read applications. Made in USA. Improve: Stabilization - Progressive spring rate lets SumoSprings compress smoothly with less resistance, & provide more resistance as they compress further. | Supersprings International Inc SumoSpring, SSR-325-47 Made in USA