When mailing a check or other private information, these #10 security envelopes with gummed closure give you additional security that your mail will not only stay sealed for its journey, but that it will also be protected from prying eyes due to the interior security print. Plus, the envelopes are windowless, so printing, adding a label, or addressing by hand are all much easier. There are 24 packs of 40 security envelopes in each case, perfect for businesses that mail a lot of private documents.