Primus Easy Fuel Duo (Piezo) Easy Fuel is all that the name implies - a gas stove that is very easy to use thanks to its sturdy and reliable design, and the fact that it is equipped with a piezo igniter. The version with a Duo valve fits most gas cartridges with a valve on the market. The perfect stove for the global traveler. The Easy Fuel is also available with the standard threaded connection. Comes with a nylon stuff sack. Gas is not included.