#4 envelopes are a particular style of announcement envelope with a large, pointed seal flap and diagonal seams most commonly used for greeting cards. #4 Baronial envelopes measure 3-5/8" x 5-1/8" in size and are made with white sulphite paper. #4 Baronial envelopes are perfect for that formal look when sending invitations. The Supplies Shops also offers the panel cards that would fit these envelopes.