Abstract: A filler neck for the fuel tank of a motor vehicle has a funnel insert having a lockable flap with a lock, which is held by two elements which can each be pivoted about a pin. The flap is released only when both elements are pivoted to one side simultaneously by the filler tube of a gas pump nozzle. In order to open the flap with minimal actuating forces, the first element can be pivoted about a first pin and holds the hinge pin for the flap on its end far from the first pin, and the second element can be pivoted about a second pin and forms a locking hook. The two pins have a spatial distance from one another in the transverse direction and the two elements are loaded with respect to one another by at least one spring.