These small plastic fresnel magnifiers offer a light weight, non-breakable alternative to your reading glasses or a glass lens magnifier. They provide a 2X magnification when held about 2” away from the map. These magnifiers have a hole in the corner for a lanyard and come packaged in a protective sleeve. They are available in two sizes. A fresnel lens replaces the curved surface of a conventional lens with a series of concentric groves molded into the surface of a thin, lightweight plastic sheet. The grooves act as individual refracting surfaces, like tiny prisms when viewed in cross sections, bending parallel rays in a very close approximation to a common focal length which, designed properly, is more efficient at gathering light then a standard lens.
|Dimensions||4.75 x 4.75 x 0.020 in|
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