Bifocal lenses are lenses with two reading areas, that are separated by a visible line, which distinguishes these lenses from the new progressive lines which do not have a visible line. The most common bifocal lenses are designed with a half-moon shaped reading area in the bottom half of the lens, called a "flat top".
However, some people prefer the "executive" or “Franklin” style, in which the lens is bisected by a horizontal line across the entire width of the lens. We supply the flat top 28 unless you specify otherwise. Bifocal lenses are the most cost effective way to create a lens with two viewing areas. In the past, most bifocal lenses were made with a distance and a reading area; nowadays, people are making bifocals with an intermediate area for computer and pad use, together with either a distance area or a reading area.