And, we also can offer full watertight trailers if this is a requirement for your application. Warren ejector trailers come standard with a 16″ tall watertight seal. We highly recommend AR-450 high tensile steel trailers for severe environments. We manufacture these trailers in aluminum, mild steel, or AR-450 high tensile strength steel. Numerous tarp systems and other roof options are available for open top ejector trailers. Spec your ejector trailer with a closed or open top trailer design. As a result, Warren builds both styles of transfer trailers. Seems like many municipalities and contract haulers prefer an ejector style trailer in lieu of a live floor trailer.