Our 130x130mm square envelope size is often used as a square greeting card envelope or an envelope for a slightly smaller square invitation. This is because you can usually (check with your Post Office) post it in Australia for the cost of a standard letter. Our envelopes are made in Australia right on our premises from premium papers, so there is no middle man and we have over 30 colours, paper finishes and seal flap styles in our 130x130mm envelope range, which is often referred to as a U.S. size 5x5 (inches).