Light pens can be used on any size screen. Pens offer more active and accurate interaction between the user and the system. Light pens give the user the full range of mouse capabilities, without the use of a pad or any horizontal surface.
Users can interact more with the application, in such modes as drag and drop, or highlighting.
To avoid false selections, the buttons have to be overly large. Light pens, in addition to a cursor, give the user acknowledgement from separate switch mechanisms, such as keyboard keys, or the nosetip or side switch on the pen itself. Touching the screen leaves a smudge. The screen has to be cleaned often in order not to present a dirty appearance. Some touch screens use an overlay that can affect the quality of the image.