There is provided a holder (300) for an inhaler article (200), the holder (300) comprising an inhalation volume estimator (350) and an air flow passage (322). The inhalation volume estimator (350) comprises a turbine (352) and an indicator coupled to the turbine (352) for indicating inhalation volume information relating to a volume of an air flow through the air flow passage (322). In use, the turbine (352) is configured to rotate in response to air flow through the air flow passage (322) and alter the inhalation volume information indicated by the indicator. An inhalation system (100) comprising the holder (300) is also provided.