Rifkin’s patented Keyless Security™ Interoffice Mail Bag is a low-cost, reusable bag that holds significantly more than a traditional manila envelope and has the added benefit of built-in, tamper evident security. For tamper-evident protection, the bag can be secured with a one-time-use, numbered plastic seal inserted in the Keyless Security™ closure. Any unauthorized access or tampering will quickly be noticed due to the lack of a security seal or the presence of a differently numbered or broken seal.