The LP-35 kit is designed for full sized pickup trucks, vans, RVs, and sport utility vehicles. The kit contains 2 heavy duty leaf assemblies that run over both sides of the axle. * Necessary Mounting Hardware Included or Listed Above Hellwig's steel leaf helper springs are ideal for helping manage your load more efficiently. They are simple to install bolting on to your new or old factory rear leaf springs and require little or no maintenance. The kits come in two versions; Constant load kits for full time suspension support; ideal where loads are typically more constant, such as on contractor/commercial service trucks and motor homes. Progressive load kits can be adjusted for additional level load carrying assistance when hauling an occasional load of fire wood or towing a trailer. Factory ride and handling characteristics are unaffected when vehicle is not loaded.