Abstract: This invention relates to pneumatic shunt resistance, comprising a block (2) having a gas-containing longitudinal cavity (4) intersected by a likewise longitudinal measurement cavity (6). The two cavities are arranged such that the measurement cavity (6) intersects the gas-containing cavity (4) so as to define a sectional region, wherein, in sections perpendicular to its longitudinal extension, the measurement cavity (6) has a similar cross-section in the sectional region of the two cavities. The pneumatic shunt resistance moreover comprises a resistor (13) located in the sectional region of the two cavities and having a shape similar to that of the measurement cavity (6) at this point, so that a gap remains between the wall of the resistor (13) and the wall of the measurement cavity. Furthermore, this invention relates to gas mixers having two flow control loops and one block, thereby reducing the number of tubes.