We have ordered this products many times before and will in the future. We use them so often for so many uses... the clasp works just fine!
The quality of products like flat clasp kraft mailing envelopes can vary dramatically by brand and seller--I've come across these types of envelopes that were so flimsy I didn't feel it was safe to actually mail out documents in them. A good rule of thumb is probably if the price seems amazingly low the quality more likely than not will follow because more often than not you get what you pay for. These are above average quality-wise and are sufficiently sturdy for mailing documents. The paper quality is good enough as long as you aren't overstuffing the contents--in which case I would recommend envelopes made with heavier material. The glue seal for the bottom flap seems secure. The adhesive you moisten to seal the envelope is strong but the edges of the flap didn't glue 100% flat on the envelopes I used. I doubt that the envelope will come open in transit but, at the same time, if you want a seal that's completely secure you will probably need to add a piece of packing tape along the bottom of the flap. These are ultimately fine for mailing a limited number of documents but for mailing out collectibles like autographed photos or something similar where cardboard will be inserted so the envelope contents don't bend I would look for something heavier.
I teach classes that require a great number of printed submissions. I give out these envelopes on the first day with the students' names on them, and they submit their papers in them. When I return the graded papers, the grades and comments are inside, allowing the students privacy. Good price, fast delivery.
Given the price, I was expecting thin and flimsy envelopes and I received the opposite. They are really good and has a great quality. It is the best in terms of prive and value review image