Designed to accommodate Orbits Vote Envelopes MF with 2-Window Envelopes, which allow you to see the title of the bill (receipt, invoice, etc.). Compatible with inkjet printers, digital printers, and perforated printers. Please note that the laser printer may have some wrinkles than the model. Fits A4-format tri-fold and 3-section sections perfectly. The envelopes have double sided tape on the lid for smooth seal after sealing the paper. In addition, since the window is made of glass paper, it can be recycled without sorting, it is environmentally friendly. We created an ecology and economy concept.