Columbian CO815 12x16x2-Inch Tyvek Expansion First Class Mail White Envelopes, 100 Count Envelope designed for ultimate protection. Protect what's inside. Superior moisture, burst and tear resistant protection. Ideal for mailing bulky items and materials. Excellent alternative to boxes and cartons. Convenient and secure self-sealing Grip-Seal closure. Simply peel off release strip and press down for a quick, secure seal. First Class border ensures priority attention. Lightweight white Tyvek material. Open end closure. 12" x 16" x 2" 100 envelopes