This is a rectangle 42 gallon diamond plate aluminum diesel auxiliary tank only. This auxiliary tank is designed for use with our Fuel Shotz diesel auxiliary installation kit. This Fuel Shotz system connects the auxiliary tank to the factory tank via the factory fill neck hose. This system keeps the factory tank full until the auxiliary tank is empty. The Fuel Shotz installation system is quick and easy to install with no wires or switches necessary. Diesel auxiliary tanks can also be used to feed generators or other equipment.