Columbian #10 Business Envelopes, Grip-Seal, Security Tinted, Non-Window, 4-1/8" x 9-1/2", 500 Per Box, White (CO145) Columbian #10 envelopes are security tinted for added privacy and confidentiality; premium 24 lb. white wove stock; 4.12 x 9.5 inch; 500 envelopes per box Convenient and secure self-sealing Grip-Seal closure; simply peel off release strip and press down for a quick, secure seal Envelope is ideal for all business, professional and personal correspondence; made in USA