It cannot be opened without visible signs of tampering.

Multilayered Construction:The bubble mailers are made with multilayered polyethylene sheets. There are several layers of poly sheets heat bonded together to form the Air Cellular bubble layers that are sandwiched between smooth layers. Self-Adhering Envelopes: The Blue Stripe poly bubble mailers come with a self-adhesive tamperproof seal. They provides a reliable, tamper-evident tight seal to secure all enclosures. It cannot be opened without visible signs of tampering.