Security Envelope - #10, 4-1/8 x 9-1/2, Box of 500 is a dependable secure mailing envelope for everyday mailing, filing and document handling in homes, offices, schools, clinics, retail counters and busy mailrooms. It features open side. Tinted interior. 24 lb. Box of 500. Certified FSC Mix 70% - Group. Key details include #10, 4-1/8 x 9-1/2 in, 24 lb, box/pack of 500, FSC-certified where stated. The easy-to-use closure makes it simple to prepare letters, forms, invoices, statements and other documents while helping keep contents neat, protected and ready for delivery. Its practical size, pack quantity and ready-to-use design help customers choose the right supply quickly, stay organized and maintain a smooth mailing workflow for routine correspondence and administrative tasks.