While you would hope that this would be a quality product from Staples it is only average. Many times none of the seams are sealed which requires masking tape to hold the envelope together at every opening (bottom top and middle). Regardless I always use extra tape at the top and bottom now not knowing if it will reach its final destination in the mail without falling apart. But aside from Staples I have yet to find any office supply outlet which sells a quality envelope in this size. Manufacturers are simply not caring about the quality of their products anymore. Staples needs to re-evaluate affixing their name to this product.
I used to used the 6" x 9" self seal envelopes in color but for my newsletters they were a tight squeeze. I had to switch to the Brown Kraft envelopes which are sturdier too.