Larger monitors can improve the way things look on your screen and keep graphics moving faster, which are the most common reasons for an upgrade. Smaller screens can be set for higher resolutions, but the result will be images that are smaller and difficult to read or distinguish. When considering a monitor's size, be aware that its size is not the same as its viewable or usable area. Manufacturers provide the viewable screen sizes, in addition to the CRT sizes, of their monitors. Since the picture tube is inside a plastic casing, the viewable screen size is smaller than the CRT or monitor size.
Larger monitors require greater viewing distance.
The smaller the distance between dots the better the image. Dot pitch is measured in millimeters. For example a .28mm dot pitch will produce a sharper image than a .39mm dot pitch. Most monitors come with dot pitches of .25 mm to .28 mm. A shadow mask tube is less expensive to produce and more commonly used in the market.