Booklet envelopes or open side envelopes are open along the long side so that you can insert your contents easily. These are most commonly used for sending annual reports, brochures, sales information, multi page printed materials, shipping documents, special size invitations and other large size documents. They also work well when you use automatic insertion machines. These covers can easily be printed with a laser or inkjet printer. Alternately, you can use address labels available with us. The solid color envelopes in size 6 x 9 are made from acid and lignin free paper and look great.