They mount above trailer leaf spring assemblies and create a cushion between the axle and trailer frame.
Trailer SumoSprings utilize the same micro-cellular air springs as SumoSprings. Trailer SumoSprings reduce wear and tear on body-frames, windows, doors, closets, mounted TV's, and other components by minimizing bounce, hop, and sway associated with most tow-able RV's. Trailer SumoSprings for Trailer Axle, GAWR: 3000-8000 (Spring-Under Axle Configuration) - Includes line relocation bracket;Sold as a pair (left and right);Maintenance-free;Reduces and absorbs vibration;500 (lb) capacity at 50% compression;Reduces overall cost of ownership;Improves overall driver control and ride comfort;Compress up to 80% of original height with full memory rebound;Increases safety;Progressive spring rate with superior damping properties;Made from patented micro-cellular urethane;Will not leak or rupture;Never load any vehicle beyond the manufacturer's GVWR;California Residents: WARNING SuperSprings Trailer SumoSprings Air Helper Spring - TSS-106-40 Reduced sway and bounce in the trailer results in increased driver control, ride comfort, reduced maintenance costs, and reduced overall cost of trailer ownership.