NEW --Progressive Reader. One pair of glasses for All needs because these over the counter tri-focals have three reading strengths in one lens. The strongest diopter is placed strategically on the lower portion of the lens because this is where you need it most; peering down to read printed material. You need less strength to view computer monitors, as they are a little farther away. That's why the weaker strengths are located in the upper portion of the lens. These reading glasses are perfect for viewing a computer monitor, key board and objects next to the computer (see diagram. The no-line progressive trifocal are seamless, so you can barely detect when your eyes switch from one strength to the next.