Paper Accents Envelopes are perfect for greeting cards, invitations, letters, and more. Let someone know that they have received something special before its even opened. These envelopes are acid-free, lignin-free, buffered and archival quality. Flat Flap. A7. For use with 5 x 7 inch cards. Actual envelope size: 5 1/4 x 7 1/4 inch. 50 pc. Assorted Colors.