We have always used these Easy Close Security-Tint Envelopes. You do not have to lick them; which is not safe; or cut your tongue; which hurts a lot. All you have to do is pull the tape off the back and close them. They do not come unstuck; so you do not have to re-stick them. We do not buy any others; and only purchase them at our favorite store; which is Staples.
This is my first time trying Staples #10 Easy Close Security-Tint Envelopes 100 /Box. I have used the Easy Close before but now I wanted to have the added privacy factor for mailing out checks etc. I held it up to the light and outdoors and you cannot see through them. I always dislike licking envelopes and these seal very nicely and stay sealed. I would recommend these for all these reasons and the price compared to the name brands was so much cheaper and worked just as well. I will be sticking with using these envelopes.