I have ordered and used this product for many years. It is easy to use and keeps the contents of the envelope opaque. However in the last batch of 500 that I bought the adhesive seems to have been much weakened so that it is difficult to keep the envelope sealed without the use of adhesive tape. I am very disappointed in this change in quality and will not order this product again.
I mail out many things and when I started to use this product it made my life easier. I have hated the taste when I had to lick the envelopes and I got paper cuts on my tong.
The heavier paper better gluing and peal-off strips for sealing make these envelopes well worth the small incremental cost above "lick-and-seal" envelopes. Opacity makes them good for mailing checks. After licking 200 envelopes for a fund-raiser I swore never again and have been using the self-stick ever since. Takes a little getting accustomed to to make sure the flap sits in the right place before sticking but that's pretty intuitive. Now if I can get the manufacturers to do the same with invitation envelopes!
These envelopes worked perfectly for our soccer club. The windows on the outside of the envelope made reading addresses easy to read and thus mail out to p ayers and coaches and parents The easy peel off tab on the back of the self sealing envelope made these envelopes quick and efficient to seal and send out to addressees. I can't ever imagine using another type of envelope. I would recommend these envelopes for anyone who is doing bulk mailing like our soccer club does every fall.