The single window is positioned to display the name and address without revealing additional personal information. Window dimensions are 4 1/2 inches x 1 inch and is positioned 4 1/4 inches from the left edge and 1 9/16 inches from the bottom. Envelope dimensions are 4 1/2 inches x 9 1/2 inches. Each #10 1/2 envelope is made of 24 lb white wove paper with side seams and measures 4 1/8 (h) x 9 1/2 (w); the single right position window measures 4 1/2 x 1 and is positioned 4 1/4 from the left edge and 1 9/16 from the bottom of the envelope Envelopes seal closed by simply adding moisture to the gummed, commercial flap. Security tint envelopes protect sensitive data; a reflex blue pattern obscures the details of what's inside, even when held up to light Healthcare claim security envelopes are made of 24 lb white wove paper with side seams for a clean, professional look. Envelopes seal closed by simply adding moisture to the gummed, commercial flap Blank CMS-1500 #10 Envelopes Gummed No. 10 1/2 envelopes are designed for use with Insurance Form CMS-1500 & similar forms. The 1" x 4-1/2" window positioned 4-1/4" from the left & 19/16" from the bottom of the envelope Bulk Business Envelopes Quality Park Window Envelope, Address Window, #10 (4 1/8 X 9 1/2), Gummed, 500/B Healthcare Form Envelopes Just add a little moisture to the glue strip along the envelope flap and seal tightly closed; no strip to peel off and throw away These claim form envelopes also have a reflex blue pattern to further protect sensitive information because the contents are not visible even when held up to light.