Desktop Publishing Supplies Brand White 6" x 9" Economy Envelopes are made for use with 5 1/2" x 8 1/2" invitations or half fold greeting cards! These White bi-fold and flat card envelopes are made from a 28 lb bond / 70 lb text (105 gsm) paper. Our White 6" x 9" envelopes measure 6" x 9" and feature a gummed booklet style square flap.