Aerochambers; Inhaler attachments for assisting in use of inhalers; Chambers for inhalers; Medical apparatus for facilitating the inhalation of pharmaceutical preparations; Nebulizer attachments for assisting in use of nebulizers; Chambers for nebulizers; Valves for use in nebulizers; Valves for use in aerochambers; Valves for use in inhalers; Valves for use in medical attachments for facilitating the inhalation of pharmaceutical preparations