5 3/4 Square Invitation Envelope - 60# Cougar Natural (5.75 x 5.75 Square) - Square Announcement Series (Pkg of 50) A Quantity of 50 - 5 3/4 SQ Invitation Envelope - Natural 60# Cougar Natural Paper - Standard Gummed Flap. The outside dimension of this envelope is 5 3/4 x 5 3/4. This envelope is meant for invitations or inserts that are 5 1/2 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 First Class Mail