Number 11 regular envelopes are slightly larger than the standard business #10 envelope. If you want to use the #10 as return/reply you will want this envelope. A #10 will fit inside a #11. It has more room then the #10 allowing for additional folded pages. It is small enough to qualify as a letter so it will not cost extra for postage based on size. Other common uses for the #11 include using them for patient records and media kits.
Number 11 Regular, Color: White, Size 4.5”x10.375”, Weight: 24#