6 1/2 Square Invitation Envelope - Square Flap - 28# White (6 1/2 x 6 1/2) - Announcement Envelope Series (Pkg of 100) A Quantity of 100 - 6 1/2 SQ Invitation Envelope - 28# White 28# White Wove Paper - Regular Gummed Flap. The outside dimension of this envelope is 6 1/2 x 6 1/2. This envelope is meant for invitations or inserts that are 6 Square or smaller. Great for weddings, showers, anniversaries, birthdays, announcements, corporate events, and more. This envelope may be sourced from any one of a number of top brands. Ships via Priority Mail