Profile: Middlesex Office Supply Inc. offers blueprint, plan, mailing, shipping and plastic bags. Our new self-sealing blueprint bags are constructed of plain white heavy-duty, co-extruded polyethylene with a permanent peel-and-seal closure. They are lightweight, waterproof and recyclable. Our double-wall, heavy-duty Kraft bags are available in three sizes to accommodate any size of rolled blueprints. These are widely accepted by courier and postal services worldwide. Our specification and CADD bags are super heavy-duty, three-way fiberglass, reinforced Kraft mailing bags. Both bags are ideal for shipping large heavy books of specifications. The CADD bags are also designed for 11″ x 17″ CAD drawings and accommodate from 1 to more than 1,000 11″ x 17″ sheets very easily. The bags are lightweight and water-resistant. Self-sealing poly mailers are plain white, tear-resistant mailers that have a permanent peel-and-seal closure and are lightweight, waterproof, recyclable & thicker than most mailers on the market. Poly mailers are a cool tool for archiving project specification books and ring binders.