These Ryman Envelopes are C4 sized, 90gsm and come in a pack of 25.These envelopes feature a window and a peel and seal closure making them easy to use and more hygienic than standard gummed envelopes. They are ideal for sending A4 documents such as CVs which you would rather not fold. They have a blue obscuring pattern inside so that the contents does not appear visible from the outside. They would be classed as a large letter when it comes to postal charges.These C4 Ryman Envelopes are a must have for any office, school or university and are also ideal for use at home.