Never used as I hate the mask part.
This is for use with asthma inhalers as the chamber with a valve allowing you to breathe in as much or little as you can.
So if very out of breath you can take several attempts to inhale the dose.
Please give a specific one hour - or less - time slot for collection.I won't accept vague "morning/after lunch" etc times!
I'm retired so can be flexible.