Transport properties of several type I and type IIIV Eu containing clathrates with small variations in the stoichiometry of the framework atoms Ge/Ga will be presented. It will be shown that the varying properties among samples with the same structure can be understood in terms of a rigid band model where only the charge carrier concentration is changed. For samples with different structure the differences can be explained by a slightly enhanced effective band mass in the type I clathrate when compared to the type IIIV structure. Finally, the potential of Eu containing clathrates for thermoelectric applications will be discussed.