My basement was recently flooded. I had several LP records stored in the basement. After drying the original jackets they warped. Records could be washed but jackets would eventually warp the records. I needed something that would protect and store the records. These envelopes were a good size and I could write new labels on each indicating the record stored within.
I needed to mail some 11x17 papers printed on thicker card stock that would be damaged if folded (this was presentation material). These envelopes were the perfect (and only!) thing I could find in a bunch of stores to ship the papers without folding them.