Inhalers and Related Methods

An inhaler housing (14) for an inhaler (10) for inhaling inhalable substances, the inhaler having: a body (14) and a dose counter (24) with a return spring (28), wherein a distinct guide surface (162) is provided for guiding the end of the return spring into a recess (152), the distinct guide surface being wider than an entrance mouth (160) of the recess, a dose counter chamber (22) being provided which is separated from a tubular interior space (182) of the inhaler by a barrier (180), the barrier including a stepped upper wall area (184) including at least three steps (186, 188, 190, 192) at different levels, the inhaler having a valve stem block (62) having an inner bore and a valve stem block having a seal (224) in the inner bore with a second diameter which is smaller than a first diameter of the inner bore, the inhaler having a canister (150) being adapted to move during operation between 1 and 4 mm, a drive being arranged to apply a firing force of between 15N and 60N of force to the canister at a position of the canister relative to a valve stem (54) at which the canister fires.