I use the envelopes to send to clients who then return info to me or mail to IRS. These envelopes were not strong or glued sufficiently to use for this purpose. The #9 size is right to inserting into a #10 size but the quality is just too poor to send to clients. If you want to present a professional feel do not use these envelopes.
The price I saw on-line at staples.com was $ 20.00 cheaper than the store price. Their online price check was stil $ 10.00 higher than the price I saw at staples.com. Next time I'll bring the price in.