Please note this envelope size cannot be mailed via USPS. Use this envelope to send flat, bulky materials or multiple small items like coins, catalogs or jumbo cards. The opening flap is on the shorter side, which helps to keep items secure after openin g. Also called a "catalog" envelope, it is available in 39 sizes from small to extra large, and is available in white, traditional kraft, and other colors for special impact. Available with moistenable flap or self-stick Peel and Seal closures.