These envelopes are made to exact specifications to match the requirements of all the inserting machines that we sell. These envelopes are guaranteed to work very well in Neopost Hasler Formax Franco Postalia and Pitney Bowes inserting machines. If you are tired of inserting problems, try our envelopes. Buy 5 or more boxes and get huge discounts! Do you need your envelopes printed? We can do that too! Call us for details.