This strong gusset mailing bag is tamper-evident, making it ideal for mailing cash and sensitive documents. The mailing bag contains an antimicrobial additive that prevents the colonisation and spread of bacteria by up to 99.9%. The antimicrobial additives never wear off or leak from the surface and their ability to minimise microbial colonisation also reduces the potential for staining and unpleasant odours, keeping the mailing bag fresh for longer. The address window and label patch can only be accessed internally and the zip closure has a security locking device to prevent tampering in transit. The gusset expands for mailing larger and bulky items.