Designed as stabilizers for 5th wheel trailers, RVs, campers with a king pin height of 38-1/2" to 50" Reduce side-to-side and front-to-back movement of your coach Their maximum vertical load rating is 5000 pounds. Power coated finish, all steel construction Adjustable threaded hitch cup for quick and effortless stabilizing adjustment These stabilizers work in conjunction with your coach’s supporting jacks and are not intended to support the full weight of your coach. LIBRA is mainly specialized in tires and parts.They are pro in dealing tires and parts over 15 years.They have US based customer service and prioritize on product quality. Have both wholesale and retail services.Designed as stabilizers for 5th wheel trailers, RVs, campers with a king pin height of 38-1/2" to 50".