Quality Park 10 x 13 Interoffice envelopes with string & button closure for document routing. Interoffice envelopes are a must in any office. Keeps documents contained and organized while routing throughout the office. 28 lb. Red stock is durable for prolonged use. String and button closure holds up over time and is an easily accessible closure. Envelopes are formatted with 5 columns on one side with narrow ruling for signatures. Holes allow for visual acknowledgement of contents. See the full line of Quality Park envelopes for all your envelope needs!