Water activated gummed tape for sealing cartons and envelopes.
The seal is incredibly difficult to peel off, and leaves behind significant damage to the carton.
Water activated gummed tape has a natural starch adhesive that bonds to box fibres to create a super secure seal. The box fibres bond with the paper tape to create a seal that is impossible to tear off.
If someone was to tamper with a box sealed with gummed paper tape, it would be highly noticeable.