The present invention provides an aerosol device for delivering a pharmaceutical formulation by inhalation via the mouth to the lungs or to the nostril in metered doses comprising: a pressurised aerosol canister including a vial containing a pharmaceutical formulation comprising an active ingredient, a propellant and, optionally, a co-solvent, the aerosol canister further comprising a metering valve having a valve stem and an actuator for the aerosol canister, the actuator including a delivery outlet and a stem block, the stem block having a receptacle into which the valve stem of the metering valve of the aerosol canister is received and axially located and being displaceable relative to the vial of the aerosol canister to actuate the metering valve of the aerosol canister, a sump extending below the receptacle, the stem block further defining a discharge orifice arranged to direct the pharmaceutical formulation through the delivery outlet, a transfer tunnel having an input opening and an output opening through which a dispensed dose of the pharmaceutical formulation is able to pass from the sump to the discharge orifice, and a land length defining the distance from between the input opening and output opening, wherein the input opening and the output opening have cross-sectional areas of from 0.002 to 0.8 mm2 and the cross-sectional area of the input opening is smaller than the cross-sectional area of the output opening, and wherein the land length is from 0.5 mm to 10 mm.
