No. 9 Double Window Envelopes display both sender and receiver addresses to mail statements and invoices. Envelopes feature a self-sealing, Redi-Seal closure. Simply lift the bottom flap and press to the top flap for an instant, secure seal. Reflex blue pattern protects sensitive client information by obscuring the details of the contents even when held up to light. 24 lb. white wove envelopes feature side seams for a clean, professional look. 3-7/8" x 8-7/8" envelopes include a top window that measures 1-3/16" x 3-1/2" and positioned 3/8" from the left and 2" from the bottom. Bottom window measures 1" x 4" and is 3/8" from the left and 1/2" from the bottom.No. 9 Double Window Envelopes display both sender and receiver addresses to mail statements and invoices. Envelopes feature a self-sealing, Redi-Seal closure. Simply lift the bottom flap and press to the top flap for an instant, secure seal. Reflex blue pattern protects sensitive client information by obscuring the details of the contents even when held up to light. 24 lb. white wove envelopes feature side seams for a clean, professional look. 3-7/8" x 8-7/8" envelopes include a top window that measures 1-3/16" x 3-1/2" and positioned 3/8" from the left and 2" from the bottom. Bottom window measures 1" x 4" and is 3/8" from the left and 1/2" from the bottom.