These Ryman Heavy Duty Envelopes are 353x 229mm, 115gsm & come in a pack of 25. These envelopes are heavy weight to ensure documents are safe during postal transport & have a peel & seal closure making them easy to use & more hygienic than standard gummed envelopes. Their unique size makes them ideal for sending multiple A5 sheets & folded A4 documents. They would also be classed as a large letter when it comes to postal charges. These Ryman Heavy Duty Envelopes are ideal to be used in schools, at home & in the office as they can be used for a variety of everyday purposes.