Acko #10 Double Window Security Business Mailing Envelopes ☑This is the standard #10 envelope with double window, it can show the basic information of the invoice, statements or documents, can easily display postal addresses. ☑Acko's envelopes outside is white, inside is blue, this is security tint protects your personal information as well as your customer's, this is very important for your business. ☑In the modern world of business, too many people have forgotten the value of an old-fashioned letter. If you are the one who use the modern methods and also use the old-fashioned method contact with your customers, maybe you can get more business chance than your competitors. ☑Simply by reaching your customers through the mail, you are instantly placing yourself in their homes, providing a physical reminder of your products and services. A letter is much harder to ignore than an email.