C-Line 35107 Clear Super Heavyweight Poly Envelopes With Velcro Closure, For 8-1/2 x 11" Document storage, Pack of 5. Biodegradable Reusable Poly Envelopes are made from acid-free, archival quality polypropylene which contains an additional additive that allows it to biodegrade when tested according to the ASTM D5511. Side loading. Overall size: 13 x 9-3/8".