These high end computer reading glasses feature specially designed lenses that allow you to see both close-up AND intermediate objects clearly and comfortably. The thin, light weight lenses automatically change in power without any lines! Plain readers only correct for your reading distance. Objects that are just inches further away may appear blurred or even distorted, that?s because the power that allows you to see an object up close, is too strong for viewing intermediate objects like your computer screen. This great pair of readers uses a CR39 asapheric designed scratch resistant lens with no visible lines. Frames are high end optical quality with spring hinges. Here's the optical sizing scoop: Lens: 44mm Bridge: 20mm Temple: 135mm