Simply peel back strip and fold closed. 1-1/8″ x 4-1/2″ window is positioned 7/8″ from left and 1/2″ from bottom. No. 10 envelopes are security-tinted for privacy of contents and made of 24 lb. No. 10 envelopes are security-tinted for privacy to protect the privacy of your contents and made of 24 lb.