No. 9 double window security envelopes with self seal closure designed for QuickBooks invoice alignment, featuring flip-and-seal speed for quick handling without peel strips or moisture. Security tint reduces read-through to protect account details during billing and statement mailings. Measures 3 7/8 x 8 7/8 inches for standard invoice folds, holds 1-2 page documents. Made from 24lb white paper in 500-count pack for recurring invoicing workflows. Weight: 5.41 pounds.