There are 2 sorts of envelopes for our private stationery range:
Gummed diamond-flapped ones are made for us specially from thick papers. They have an “infinite” shelf life. Due to the heavy stock used, a stronger glue is necessary.
Peel-and-seal ones are manufactured by the million, and usually have Conqueror printed inside. Their shelf life is about a year and they are less expensive.
![This picture shows the difference:](https://geebrothers.co.uk/wp-content/uploads/2017/01/envflap.jpg)