The ones who get a white ball serve in a Batallón del Servicio Militar Nacional (National Military Service Battalion) composed entirely of one-year SMN conscripts. In certain cities, such as Veracruz and Ciudad Madero, the lottery system also includes a blue ball; whoever draws it must serve in the navy. Military service is also (voluntarily) open to women. Conscripts are trained in basic combat with fire weapons, in one Infantry Battalion.