Columbian Brown Kraft String & Button 10 x 13 Inch Interdepartment Envelopes 100 Count (CO880) For confidential routing of interdepartmental documents. Long-life string &amp; button closure designed for repeated use. Double-sided printing with a five column format. Heavy-duty 28lb brown kraft material. Opaque brown kraft material provides privacy of contents. 10" x 13" 100 envelopes Brown Kraft 10 x 13 interoffice envelope with a 28-lb. paper stock features a string-tie and button closure. Preprinted information saves time, money. Five-column standard style interoffice envelope includes spaces for important information for routing. String-tie and button closure. Reusable envelopes