ThinOptics reading glasses are offered with the following optical strength options: 1.00 (Low), 1.50 (Low-Mid), 2.00 (Medium) and 2.50 (High). The Low covers a range 0.75 to 1.25, the low-mid covers a range of 1.25 to 1.75, the medium covers a range of 1.75 to 2.25, and the high covers a range of 2.25 to 2.75. You will want to choose the option that most closely matches your needs. However, since reading glasses are optimized for short-distance reading usage, you will automatically adjust the reading distance between your eyes and the object you are reading. Since ThinOptics reading glasses cover optical strengths ranging between 1.00 to 2.75, nearly all people requiring reading glasses will find a ThinOptics reading glasses option that suits them.