The RVK3270 Patriot 16,000-pound, rail-mounted fifth wheel slider from B & W Trailer Hitches features two solid 1-inch tubular steel carriage rails with sturdy center supports to prevent deforming or binding from load flex. Hourglass-shaped rollers convey the carriage mechanism, regardless of topography. The hitch accommodates 12 inches of slide. Vertical adjustments can be made from 17 to 19 inches, providing clearance for taller truck-bed walls. 800/810-4918; www.turnoverball.com.