The oldest lights developed on railroad crossings are the 8x20 inch lights. 8x20 means that the glass or plastic lens is 8 inches, and the visor is 20 inches. Made by almost every railroad supply company before 1980, these were used on most railroad signals from the 1910s to the 1980s. The incandescent lights have become obsolete, matched by modern, brighter, and easier to maintain LED lights. The standard for most railroad lights is now 12x24 inches. Many railroad companies have been replacing the light house or converting the bulbs to LED lights. Luckily, many short-line companies have vast numbers of 8 Inch lights.