Refer to figures.
An electronic flight instrument system (EFIS) is a flight deck instrument display system in which the display technology used is electronic rather than electromechanical. Although cathode ray tube (CRT) displays were used at first, liquid crystal displays (LCD) are now more common due to their relatively little power needed for operation.

• Cathode Ray Tubes (CRT) are known to be too bulky and impractical to fit. During their operation, compared to LCD, CRT displays require more power and generate a lot of heat that needs to be dissipated by active cooling systems.
• LCD displays have a much lower current consumption (60W for an A320), have no screen burn, have a larger view area, and do not produce radiation, and are much lighter by at least half the mass of a CTR screen.