These are solid enough to mail a magazine in. I have never had a problem with them ripping apart. I have mailed hundreds of these envelopes after sealing the open end with a piece of packing tape (I don't use the gummed flap but maybe I should). The price is decent.
We are an educational non-profit serving about 45 schools a year. We use boxes and boxes of 9 x 13 brown envelopes! The quality of these is good and we especially like the clasp closing so students' handouts do not fall out and get lost in their desks and still they can use them every week we are in session. We have also found the product to be a good value. We have 'shopped around" somewhat and our experience shows that the price at Staples is as good if not better than other places we have tried. And they are always in stock at the store so ordering ahead is not necessary.
Our publishing company offers monthly subscriptions to our readers and to insure that they receiving a pristine copy each month we use the brown Kraft clasp envelopes. They have proven to be of top quality construction and the most reliable time and time again. And with just a click of the mouse our purchasing department can order on-line anytime and have the added value of free deliver within a day or two with a minimum purchase from Staples. I challenge anyone to find a better value...anywhere.