This RDS 20-gallon auxiliary tank is a gravity-feed diesel tank that lets user increase their driving range and shop for better fuel prices. No more constant stopping when pulling a travel trailer or 5th wheel. Intended for highway use with diesel. Fits under a low profile toolbox. It is the user’s responsibility to comply with local, state and federal requirements pertaining to safe transportation, loading, and discharging of tank contents. U.S.A.