On cathode ray tube monitors, VIS differs noticeably from the full tube size, which is generally about 25mm or one inch larger.
Liquid crystal displays use 100% of their surface to display, thus the VIS is the actual size presented to the viewer.
In the U.S, manufacturers and retailers are allowed to list the tube size, which is misleading and confusing to many customers, especially when comparing both CRT and LCD models together. In many other countries, this practice is prohibited by consumer-protection laws.