10" x 13" First Class Envelopes get your package delivered first-class by USPS. Green diamond, first-class border grabs your recipient's attention in the mailbox. Redi-Seal closure features a pressure-activated latex adhesive with a unique, double-flap design to keep the gum from sticking before use. Simply raise the lower flap and press to seal - no paper strips or moisture required. Redi-Seal envelopes are the perfect mailroom update for concerns about surface germs while saving time and cutting waste with every mailing. Envelopes are compatible with inkjet printers but are not recommended for laser printers. 28 lb. white wove stock withstands extensive handling. Center seams add strength for heavy contents. First-class envelopes are ideal for sales literature, newsletters, contracts and more. They're a cost-effective way to send important letters and lightweight packages.