The Doepker RockR Super B gives aggregate haulers a decisive advantage on longer runs, pairing two 21-foot Hardox 450 tubs for roughly 25 cubic yards per trailer. Its defining feature is side-selectable unloading: with two retention pins removed, the operator directs discharge to the driver's side or curb side without repositioning the trailer. High-tensile main beams and a 12,020 kg tare weight keep the combination light enough to haul commercially while standing up to the abrasion that ends ordinary gravel trailers early.