They are premium envelopes wherein nylon threads are mounted on ledger paper which is then coated with HDP (High Density Polyethylene). Self adhesive silicon tape on the flap makes it temper evident. HDP coating also makes the envelope water resistant to some extent.
They have wide range of application from storing to mailing purpose. They are widely used for courier purpose in today’s digital world of online shopping where they are used for sending parcels from one place to another.