Standard #9 Windowless Envelopes Measure 3 7/8 x 8 7/8 Popular remittance Size Envelope for Both Home & Business Mailing and Fits perfectly inside Standard #10 Business Envelopes. Wide Enough to hold Standard 8.5 x 11 Size Papers, Letters, Checks, Invoices and More 500 Security Envelopes with Heavy Tint Pattern to Hide all What is inside Envelope Flap has Strong Adhesive Which is Activated when moisten to Keep Contents Secure These Envelopes are Made of Durable 24lb. White Wove Paper Which is smooth for Both Laser and Inkjet Printers Proudly Made Right Here in the USA