No. 10 invoice envelopes offer a self-sealing design that makes envelopes quick and easy to close. 24 lb. envelopes require no moisture to seal. Unique double-flap design keeps the gum from sticking before use. Simply raise the lower flap and press. #10 (4.12″ x 9.5″) – 24lb – Self-sealing – 500 / Box – White