Jet fuel
Jet fuel is clear to straw-colored, and is dispensed from a special nozzle called a J spout or duckbill that has a rectangular opening larger than 60 mm diagonally, so as not to fit into avgas ports. However, some jet and turbine aircraft, such as some models of the Astar helicopter, have a fueling port too small for the J spout, and thus require a smaller nozzle.