We do mass mailings of seminar announcements several times a year. These envelopes make the task much easier and the ready to mail product is sufficiently secure. It takes less than half the time it would take with glued envelopes where the glue has to be dampened in order to seal.
I use these envelopes every year to send out the info packet to about 500 people. They are easy to stuff and the job gets done quickly. I wish the peel and seal would come in the catalog size as well.
We use these mailers for a variety of purposes and often have to send CD ROMs within jewel cases along with our documentation. They arrive without any problems...as far as I know. But as I can open the seal once in place any sensitive material causes me to tape over the sealed flap. However having the ability to reopen a sealed envelope has also been a benefit when I've forgotten to place something in the package. Overall...I will continue to purchase these catalog envelopes from Staples. No one makes a better envelope at this cost so I wouldn't bother spending time looking around.
I use these envelopes regularly for mass mailings because they save time versus moistening and pressing gummed envelope flaps. They haven't failed me in over 10 years of use.