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.