We include a sheet like this in most of our cases. It is so the inside of the case does not rust during transport or while it's on the shelf of your favorite computer store.
You can dispose of it once you unbox your case, though.
Thank you! Always great to hear it straight from the manufacturer!
this really helped me. got CM Elite, and was really confused on what to do with the weird paper. tried visiting the website but its no longer available. Thank You for providing this answer, even though old thread it helped.