Because the flip-over ball rotates in its socket, hitch ball and coupler life are greatly extended. They don't "grind" against each other when you tow. The other advantage of a rotating ball is that it stays "free" in its socket so you can easily remove the ball for storage or needing a flat bed space. Installs behind fifth-wheel on standard 34" frames Requires 10" on top of the frame and 4" down each side of frame Mounts with three 3/4" bolts on each side Rated for 30,000 lbs. Complete with 2 5/16" ball and mounting hardware MODEL NO - 205ST30K