These envelopes will safely protect your stock certificates as well as similarly sized items including birth certificates, awards, and marriage licenses. They are sealed on three sides, with one long side open to allow easy insertion. We use archival .004 in. thick crystal clear polyester to manufacture these. General purpose envelopes are sealed on three sides and open on one long side. These sizes fit comfortably in standard archival boxes including document cases and drop front boxes. 10 per package.