Quality Park #9 Double Window Envelopes have layered privacy features to keep checks secure. Reveal-N-Seal self seal envelope flaps are perforated to show evidence of tampering. Opaque envelope sides have a complex security pattern inside that obscures letters and numbers, even when held to light. Careful window placement shows only the sender and receiver addresses while check amounts and other data remain private and protected. Built for Finance & Accounting: These double window envelopes are compatible with most 3-7/8" x 8-7/8" invoices and statements. Made with modern side-seam construction in crisp, bright white 24 lb white wove paper. Our patented seal prevents waste two ways. The fold-in-place lower flap on these safety envelopes can't stick prematurely, so there are no wasted envelopes in your box — just lift the bottom flap when you're ready and press to seal. Plus, the fold-in-place envelope flap means there's no peel-away strip mess to clean up later. The innovative design also preserves the adhesive and lengthens shelf life until use. Available in boxes of 500 so you never run out! Envelope dimensions are 3 7/8 x 8 7/8 inches. Top window dimensions are 1-3/16 x 3-1/2 inches, 3/8 inches from the left and 2 inches from the bottom. Bottom window dimensions are 1 x 4 inches, 3/8 inch from the left and a 1/2 inch from the bottom.