Collagen Casings Require Refrigeration?

Are they cellulose or collagen?
I don't see and mahogany cellulose on their website.
Collagen don't have to be refrigerated but it helps them last and not get brittle. If they do get a little brittle they can be soaked for a few minutes to help soften them.
I'm not familiar with cellulose but I found this on another website:
Stored in a cool and dry place. The remaining strands should be placed in an airtight bag in order to prevent drying out
Stored under the recommended conditions, can be used up to one year after receipt