Mask recommendations

i can't wear jocket after getting these. material is much softer. it does not expand and contract on breathing which was very annoying with Jockey (some people prefer that). and these do not have nose clips so might not be for everyone. but these are so comfortable that i can wear them throughout the day without them getting annoying.
 
How do we determine which size fits us best?? There are just no guidelines to help us make an informed decision which size to go for. Seems like trial and error.
 

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