These printers can print a whole page at one command, offer highest quality and can combine text, graphics, etc. They are generally restricted to A4 paper and black and white, though transparencies can also be printed. Colour laser printers are now available but at very high prices. Laser printers are mostly used in electronic publishing. Future prospects for output devices include: high quality display screens of different sizes, more wide spread use of laser, and similar page printers, greater availability of cheap and versatile thermal printers and a greater role for voice output, etc.