Keep sensitive information safe with this 500-pack of Quality Park security-tinted left-window #10 Redi-Strip envelopes. Get a high-quality mailing experience with these Redi-Strip envelopes. Made with a strong acid-free coat, these envelopes are resistant to crumbling and yellowing with age. Featuring a blue-tinted interior, these envelopes keep confidential information protected, even when held up to a light. These Quality Park Redi-Strip envelopes come 500 per pack and have a left-window design, making shipping addresses readable.