The main difference between booklet vs catalog envelopes, plus dimensions of booklet envelopes and dimensions for enclosed print pieces.
Booklet vs Catalog Envelopes
6 x 9 Booklet Envelopes with Peel & Stick, 28lb. Bright White
6 x 9 Booklet Envelopes Order Custom 6 x 9 Booklet Envelopes Online at U.S. Press
Booklet Envelope Printing for Custom and Standard Sizes
Catalog Envelopes 9'' x 12
Envelope Sizes and Their Uses - BeagleLegal
Custom Printed 9 x 12 Booklet Envelopes with Gum Adhesive
Custom 10x13 Booklet Envelopes
Booklet and Catalog Envelopes
Catalog and Booklet Envelopes