5 3/4 Square Invitation Envelope - 28# Cougar White (5.75 x 5.75) - Square Announcement Series (Box of 1000) A Quantity of 1000 - 5 3/4 SQ Invitation Envelope - White 28# Cougar White Paper - Smooth Finish - 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 UPS Ground