Review on 40 #10 Security Tinted Self-Seal Envelopes - No Window, 24 LB White EnveGuard Size 4-1/8 X 9-1/2 Inches - 40 Count (34140) by Jonathan Sriubas

The envolopes are ok if you are mailing very thin letters/ insert material. In the above photo, you will note the comparison of the back of two # 10 envolopes. There is 1/4 inch difference. This is an important 1/4 inch if you are mailing a thicker letter. The pre-stick flap sticks to your letter not the envolope. So you have to put in an "extender" to cover the shortage, then tape it closed! Not good.