Cut the time it takes you to pay bills with these envelopes - just stuff, seal and send. They're designed to be perfect companions to your checks. These #9 double-window envelopes accommodate most 8.5-by-11-inch computer-generated statements and invoices. Since business correspondence often includes personal account or client information, Quality Forms invoice envelopes offers the ultimate in protection, privacy and confidentiality when mailing invoice documents. The envelopes feature plastic windows and an inner security tint that prevents documents from being read through the envelope when held up to the light. The woven paper can stand up to significant wear and tear, so there's no need to worry about the envelope ripping open. The #9 envelopes are standardized to suit common business invoice layouts, with the windows placed just right to properly display sender and receiver details.