Crystal clear envelopes are quite revealing, leaving little to the imagination. USPS-approved and available in a variety of regular-postage sizes with moistenable flaps or peel and seal closures, these eye-openers are clearly versatile for corporate, promotional, invitation mailings, and any time you want to show your stuff. Literally. Choose from many different sizes and styles to help you find the perfect envelope for your needs. Usually used on a preprinted invitation to show through or inside another envelope.