CONVENIENT DOUBLE WINDOW: Display the sender and receiver addresses through the double window openings. Positioned to fit most invoice address layouts, this double window envelope not only saves time but also makes sure the document is delivered straight into the customer's hands! The 1-3/16" x 3-1/2" top window is positioned 3/8" from the left and 2" from the bottom. The 1" x 4" bottom window is positioned 3/8" from the left and 1/2" from the bottom..ENHANCED PRIVACY FEATURES: Protect sensitive client information with these security tinted envelopes. The reflex blue pattern lining the envelope's interior makes it impossible to see the details of the contents, even when held up to the light. Mail invoices, statements and other important documents with confidence..REVEAL-N-SEAL SELF SEAL CLOSURE: The best overall self-sealing envelope in the industry! It's patented seal design allows for an aggressive quick seal. Simply pull the bottom flap up, fold the top flap down and press to seal. A built-in security feature along the top of the flap shows indications of tampering..500 ENVELOPES IN EACH BOX: ideal for both everyday office use and bulk mailings, each box of Quality Park #9 Double Window Security Tinted Invoice and Statement Envelopes provides a long lasting supply!