I have been using this size Staples brand of envelope for well over five years now. Staples has done something that changed them and while they are not bad for the price the old envelopes were better. Now I have to tape these self sealing envelopes closed because the adhesive doesn't stick well enough. To sum it up these are good enough but not great. I would buy them again though along with other Staples Products...
Purchased these envelopes in the past for my office (small convent) and have been very happy with the quality and ease of sealing and use of envelope. I have used the clipped envelopes in the past and definitely not as efficient and much harder to work with so I now always use the easy seal envelopes when mailing larger packages for paper documents. These envelopes are very good but the catalog envelopes are stronger if enclosing bulky items such as booklets or pamphlets -- they won't rip as easily.
These are the best envelopes for us cost wise and for being sturdy. As a law firm we do send out quite a bit of mail to other attorneys and to the courts. We rarely ever have difficulties with the envelopes during mailing no matter how far they have to go. We also use these for return mailings and they same thing there they hold up quite well even though they are handled a great deal at the post office and at the Clerk of Courts offices and attorneys not to mention to and from the clients. The one thing that I would add to this envelope is the security liner for privacy issues.