Self-adhesive Redi-Strip flap provides a secure seal. Protective paper strip keeps the self-adhesive closure free of dust. Wove finish adds a professional touch. Heat-resistant adhesive. Envelope Size: 4 1/8 x 9 1/2; Envelope/Mailer Type: Business/Trade; Closure: Redi-Strip . Includes 500 envelopes per box. A Sustainable Forestry Initiative(R) (SFI) certified eco-friendly solution.