No. 10 envelopes have always been the preferred size for business mailings. It perfectly holds an 8 ½ x 11 size letterhead paper folded twice. Today we see No. 10’s being not only used for business communication, but also for invitations, holiday cards and announcements. We offer three different No. 10 envelope configurations in our SAVOY 100% pure cotton line; Square flap, Pointed flap and Policy (open end).