Several dozen. If I enjoy a snuff that I open I place the contents into one of these, then I transfer a portion I want to snuff with a clean spoon into a snuff box. Mason jars with two part lids are entirely airtight and will keep the snuff fresh. I’ve kept snuff in mason jars for years without deterioration of flavour or loss of moisture.
When I buy snuff for my cellar and they don’t come in a vacuum sealed tin I seal them in mylar bags. I first started doing this when I was buying SWS snuff for my cellar, as I didn’t want to remove them from the tin in fear of risking mold.