QUALITY PARK #9 Double Window Envelopes (8 13/16 x 3 7/8) in 24lb. Bright White are business envelopes which feature a blue security tint printed inside. Security tints protect your privacy when sending letters, invoices or statements as the tinted pattern helps discourages reading sensitive information through the outside of the envelope. The two envelope windows save the time and expense of separately addressing envelopes. Simply position the addresses printed on the document inside to show through the windows. Double Window envelopes are sealed with a moistenable strip along the top flap. Available both plain and custom printed for company branding and creative uses. Pack of 50.