A sub-assembly of a medicament delivery device including a propellant source having a reservoir for containing a propellant and a stem for dispensing propellant from the reservoir, the stem extending axially along a longitudinal axis and having an open outlet end and a bore therethrough that is in fluid communication with the open outlet end and is selectively in fluid communication with the reservoir. The sub-assembly also includes a spray head member attachable to the stem. The spray head member is arranged to radially deflect propellent passing through the bore of the stem relative to the longitudinal axis.