Get faster warming and cleaner installation with the HOT FOX fuel warmer from Arctic Fox. It truly is an in-line warmer that installs in the fuel tank. The simple 1″ (38mm) diameter stainless steel tube inserts in the tank through a standard USA fuel gauge sending unit opening. Coolant passages inside the tube surround the fuel standpipe to provide excellent heat rise. The internal fuel line features an exclusive spiral design to offer larger heat exchange surface from warm coolant to cold fuel.