Inhalers and related methods

An inhaler for the inhalation of inhalable substances, the inhaler comprising:

• a main body and a cap housing defining an interior chamber;
• a canister enclosed within the interior chamber having an interior reservoir containing pressurised inhalable substances including fluid;
• a metering valve including a metering chamber and a valve stem defining a communication path between the metering chamber and the interior reservoir, the communication path including an first opening configured to permit flow between a transfer space inside the valve stem and the interior reservoir, the interior reservoir being arranged for orientation above the metering chamber whereby gas located within the metering chamber is replaced with liquid from the interior reservoir;
• and
• wherein a lock system is provided for locking the cap housing on the main body;
• the lock system including helical threads having non-overlapping and distinct thread segments for providing rotational attachment of the cap housing to the main body and a first lock member that cooperates with a second lock member to achieve a snap lock between the cap housing and the main body when the cap housing is rotationally attached to the main body in a locked position;
• wherein the thread segments are radially disposed about a central axis and arranged such that the thread segments are non-overlapping with respect to each other along the central axis;
• and
• wherein the first lock member is interposed between the thread segments.