Addresses appear through window - no need to hand-address Fully gummed flap provides a strong, dependable seal. Made with crisp 24-lb white wove for a substantial feel. Quality Park Security Envelopes - Single Window - #10 (4.13in. x 9.50in.) - 24 lb - Gummed - Wove - 500 / Box - White is one of many Business Envelopes available through Office Depot. Made by Quality Park.