We can offer two types of Generator Fuel tanks. One is a generator sub base tank that typically get used in outdoor applications where there is a generator and an enclosure mounted on top of the tank. The sub base tanks are ULC S601 Listed. The second type of tank is a ULC S602 Listed obround style tank. These can be used both indoors and outdoors, and typically need to be Double Wall Vacuum Monitored for generator fuel applications. We can custom design tanks up to a point to work for a specific application.