5 1/2 Square Invitation Envelope - White (5.5 x 5.5) - Announcement Envelope Series (Pkg of 100) A Quantity of 100 - 5 1/2 SQ Invitation Envelope - 28# White 28# White Wove Paper - Regular Gummed Flap. The outside dimension of this envelope is 5 1/2 x 5 1/2. This envelope is meant for invitations or inserts that are 5 Square or smaller. Perfect for Greeting cards, Weddings or any announcement. This envelope may be sourced from any one of a number of top brands. Ships via Priority Mail