Customization isn’t solely for looks. Instead, #9 custom envelopes offer convenience and better security. Up to two inks – colors of your choice – assist with the visual aspect of a mailer, but we offer far more. All #9 envelopes, for returns or replies, fulfill USPS requirements and can have standard or confidential paper, which guards against fraud and nosey snoopers. If customer correspondence must be accompanied by a return envelope, work with us to create the precise custom set!