Sparco Products Invoice Envelopes,Strd Window,No, 10,4-1/2""x9-1/2"",500/BX,WENo, 10 invoice envelopes offer single windows for mailing address, Compatible with most letter-size, computer-generated invoices and statements, Poly 24 lb, window envelopes have inside blue security tint for privacy of contents, Self-sealing design makes them quick and easy to close, SKU: DLRDY082324