Quality Park Interoffice Envelopes, String and Button, Brown Kraft, 10 x 13, 100 per Case, (63561) DURABLE: Made from heavyweight 28 lb. paper stock VISUAL CONFIRMATION: Holes punched on both sides of the envelope allow for visual confirmation of the contents without opening MAXIMIZE: 5 Columns on each side with narrow ruling allows for maximum space for signatures STRING-AND-BUTTON: Convenient when reusing the envelope, easy to open and close repeatedly GREAT VALUE: Conveniently packed in 100 count to reduce the frequency of repurchasing