These easy-close security-tint envelopes are all that I buy...just pull of the strip and close. The glue holds well with a little burnishing. For extra security on important documents I secure the ends of the flaps with tape...that prevents any damage occurring in the automated machines used by the post office. I purchase these in the 100s size as my needs are minimal. And the price is right!
These envelopes serve their purpose. They are well constructed and basically do what you need them to do. If there were one negative criticism about these envelopes it is that the adhesive strip closure is not well attached and sometimes sticks to the pull strip. While I have not yet had trouble with them staying closed I sometimes wonder if they will...