Envelopes can be manufactured in an almost endless number of sizes and shapes in many different styles. Almost all envelopes, however, stem from two basic construction designs: Open Side and Open End. Dozens of different designs can be developed from these two basic styles to meet the customer's particular requirements.
Open end envelopes have their opening and flap on the short side of the envelope. This style is most often used in making catalog envelopes that do not require automatic insertion and also applies to perfectly square envelopes.
The open side envelope has its opening on the long side of the envelope and typically features either diagonal or double side seams. This style is ideal for use with automatic inserting equipment. As the more common design, open side envelopes are widely used for business correspondence, direct mail marketing, and greeting cards.
From these two basic configurations, the following standard designs have evolved.
Single Side Seam