USPS Tabbing / Wafer Sealing
The post office has specific requirements regarding FSM - Folded Self-Mailers (bi-folds, tri-folds, or z-fold mailers) basically any mailer that requires the use of a tabs to keep it closed during the mailing process. Self-mailers prepared for automation rate mailings must be tabbed (secured) to prevent an open edge from jamming high-speed processing equipment. Standards for tabbing are based on basis weight of paper stock used and the location of the folded or bound edge.
