These Ryman Heavy Duty Envelopes are 254x178mm, 110gsm and come in a pack of 15.These envelopes are heavy weight to ensure documents are safe during postal transport and have a peel and seal closure making them easy to use and more hygienic than standard gummed envelopes. Their unique size makes them ideal for sending multiple A5 sheets and folded A4 documents and they would be classed as a large letter when it comes to postal charges.These Ryman Heavy Duty Envelopes are ideal for use in schools, at home and in the office as they can be used for a variety of everyday purposes.