With 4 Bars Insert Adapter In Rail Receptacle Allows For Use With 7/8 Or 1 Diameter Rails Attractive Brown Vein Finish Constructed Of 1 Steel For Strength And Durability Telescopes With Movement Of Bed Easily Adjusts Up Or Down With Spring-loaded Release Spring-loaded Crossbars Are Easy To Intall And Remove Universal Cross Brace Bars Can Be Used With Most Manufacturers Bed Rails Limited Lifetime Warranty Rails Extend From 47 - 78