Our device is connected in between the POS and the existing thermoprinter. The device requires no software installation within the POS nor the Clients an app to get their invoices but just a QR reader (currently all camera apps have a QR reader embedded). Every time a receipt is produced, a QR code is shown on the device screen. If the client wants his receipt printed, on the screen, there is a button that when pressed sends the printing order to the thermal printer to get the receipt in the paper.