I would not buy these if you still carried a better quality product as you used to. I have had the flap come open between my home and the post office. I have small stickers with our organization's logo and I use them to seal the ends of the envelopes. That gets to be a pain when I send out dozens of them each month.
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!