These are great envelopes. I use them for mailing (or forwarding) financial stuff. I can fit your Basic #10 envelope into them, no sweat! I'll order them again when I run out.
I've been using these #11 envelopes for more than 20 years as my filing system for tax receipts. The #11 envelopes are just enough larger than standard #10. They are great! I now get all my envelopes with Business Envelopes!
The quality of this envelope is great! Fast turnaround time.