I run a mail order business and use these envelopes extensively. They're good overall and of good value...but the glue used is a failure. I'd also be happier if the paper used was a bit heavier.
the best feature for my business is the seal. I ship chain wallets and these seal without having to back them up with packing tape. I have bought other companies envelopes and they don't seal without glue or packing tape which is totally frustrating.
We had a Quilt Show and sent out our program books to vendors donating door prizes which were the same size as the mailing envelopes. The only problem I had was the fold over closing section was hard to get a straight edge in the fold and the clasps were hard to open straight out. Other than those two gripes the envelopes were well made.