LUX Paper #10 Square Flap Envelopes with Peel & Press, 4 1/8" x 9 1/2" - 80lb. Bright White, 250 Pack (4860-80W-250) Size: #10 Square Flap Envelopes 4 ? in x 9  in / 4.125 x 9.5 / 104.775mm x 241.3mm Quantity: Pack of 250 Color: 80lb. Bright White is our thickest and brightest white envelope color. Perfect for a professional, high quality look. This envelope is made from quality 80lb. Text Paper. Opaque and not see through. Modern Square Back Flap. USES: Checks, Invoices, Letterhead, Personal Letters, Statements, Bills, Flyers. Applications: Business Mailings, Direct Mail, Corporate Mailings, Financial Mailings, Personal Mail. Printable on off-set printing presses and some home printers.