#9 Security Envelope, 3 7/8'' x 8 7/8'' Envelope Size Class: #9 Envelope Closure: Moisture Seal Paper Weight: 24 lb These #9 Security Envelopes feature a tinted interior lining to keep sensitive information private and secure and are perfect for a variety of applications.net/click-7658614-13706452?url=https%3A%2F%2Fwww.