Double Window Invoice Envelopes (4 1/8 x 9 1/8) Color - Mandarin Orange Pack of 50 Peel & Press Sealing Method Double Window Invoice Envelopes are specially designed to hold Quickbooks Invoices. The company name or return address will line up with and show perfectly through the top window, while the mailing address will show through the bottom window. A perfect envelope for all Quickbooks invoicing and accounting mailings.