An air mass flowmeter, suitable for connection to an air-intake manifold of an internal combustion engine, measures an air mass taken in by the engine. An elongated handle has a first end that is attached to the peripheral edge. A portion of the lower metal plate is exposed via the LED-receiving hole and an LED is mounted on the exposed portion of the lower metal plate and is electrically connected to both of the upper and lower metal plates. Preferably, the gas diffusion layers are applied as a paste to the porous metal sheet and then dried. When the dump bed is raised, as in FIG.