Quality Park® Double Window Envelopes display both sender and receiver addresses for mailing statements and invoices. Features a special Redi-Seal® self sealing closure. Simply lift the bottom flap and press to the top flap for an instant secure seal. A reflex blue pattern protects sensitive client information because it obscures the details of the contents even when held up to light. Seam Type: Diagonal; Flap Type: Commercial; Trade Size: #9; Security Tinted: Yes.