SR900ES Double Window Envelope. Top Window: 3 1/2 x 7/8″; 5/16″ from top, 5/16″ from left. 250 Per box. Bottom Window: 3 1/2 x 1″; 5/8″ from bottom, 7/8″ from left. White, Confidential Envelope. Professional style that is sure to get opened.