Shopping for Envelopes, 5.5 Square (5-1/2-x-5-1/2) found in the OffWhite Color Group --2PBasics Envelopes. Also, jump to our popular help pages for paper help. (To make a successful paper selection, it is important to have a brief understanding of text weight and cover weight papers.) AND envelope help (It is important to remember that inserts must always be smaller than the envelope dimensions.)