A magnetic inductive flow meter having a pressure-resistant plastic housing, the flow meter comprising: an inlet connecting piece ; an outlet connecting piece ; and a measuring unit arranged between the inlet connecting piece and the outlet connecting piece , the measuring unit comprising: a measuring channel with a channel wall , the measuring channel configures such that the measuring fluid flows there through; two opposing magnetic poles at the measuring channel ; and two opposing measuring electrodes oriented perpendicular to the magnetic poles in the channel wall , wherein, with consideration of the maximum permissible internal pressure for the selected plastic, the channel wall is reduced to a still permissible extent in the area of the magnetic poles , characterized by the features: - an inner reinforcement cage, having at least two inner transverse partitions and at least two inner longitudinal ribs , stabilizes the channel wall , - an outer reinforcement cage, having at least two first outer longitudinal ribs , holds and stabilizes the inner reinforcement cage and connects the measuring unit in a tension-resistant manner to the inlet connecting piece and the outlet connecting piece . an inlet connecting piece ; an outlet connecting piece ; and a measuring unit arranged between the inlet connecting piece and the outlet connecting piece , the measuring unit comprising: a measuring channel with a channel wall , the measuring channel configures such that the measuring fluid flows there through; two opposing magnetic poles at the measuring channel ; and two opposing measuring electrodes oriented perpendicular to the magnetic poles in the channel wall , wherein, with consideration of the maximum permissible internal pressure for the selected plastic, the channel wall is reduced to a still permissible extent in the area of the magnetic poles , characterized by the features: - an inner reinforcement cage, having at least two inner transverse partitions and at least two inner longitudinal ribs , stabilizes the channel wall , - an outer reinforcement cage, having at least two first outer longitudinal ribs , holds and stabilizes the inner reinforcement cage and connects the measuring unit in a tension-resistant manner to the inlet connecting piece and the outlet connecting piece . a measuring channel with a channel wall , the measuring channel configures such that the measuring fluid flows there through; two opposing magnetic poles at the measuring channel ; and two opposing measuring electrodes oriented perpendicular to the magnetic poles in the channel wall , wherein, with consideration of the maximum permissible internal pressure for the selected plastic, the channel wall is reduced to a still permissible extent in the area of the magnetic poles , characterized by the features: - an inner reinforcement cage, having at least two inner transverse partitions and at least two inner longitudinal ribs , stabilizes the channel wall , - an outer reinforcement cage, having at least two first outer longitudinal ribs , holds and stabilizes the inner reinforcement cage and connects the measuring unit in a tension-resistant manner to the inlet connecting piece and the outlet connecting piece . - an inner reinforcement cage, having at least two inner transverse partitions and at least two inner longitudinal ribs , stabilizes the channel wall , - an outer reinforcement cage, having at least two first outer longitudinal ribs , holds and stabilizes the inner reinforcement cage and connects the measuring unit in a tension-resistant manner to the inlet connecting piece and the outlet connecting piece . <EOS>