Our custom envelope printing service is great for businesses and organizations across the spectrum. Doctors, universities, non-profits, politicians, churches, you name it - anyone who wants to brand their business and give a first impression of style and professionalism can benefit from custom envelopes. We offer single- or double-sided printing on a number of envelope types. #10 envelopes are the most common business envelopes. These are available with or without a window, and with or without a self-sealing strip. #9 envelopes are the most common business reply envelopes and fit conveniently inside a #10. The 6" x 9" envelopes are good for mailing small books and invitations. 9" x 12" envelopes are ideal for sending catalogs, reports, books, and magazines.