Double envelope and seal assembly - has windows in one envelope sealed when required

摘要

A double envelope may be made of any suitable material and the inner envelope may be made of material of cigarette paper thickness. Each envelope has its own flap and individual seal. Either envelope may be transparent or fitted with windows. The envelopes are formed so that one cannot be detached from the other without tearing. It is impossible to tamper with the contents of the inner envelope without leaving a sign of this either the inner or outer envelope.