Opticlens Brand handy 5 x 7 inch page magnifier. Excellent for reading the fine print in books, magazines, maps, telephone directories, and recipes. They also work great for use in light-duty solar projects such as starting campfires, DIY solar cooking, and solar heaters. They are made from flexible high-quality, optical-grade PVC. This allows them to be thinner with less distortion as well as being lightweight and easy to hold while using. Optical PVC is virtually shatterproof for safety and peace of mind. Lens Specifications: Approximately 5" x 7.00" (Inches). Thickness: 0.4mm. Material: optical PVC. Groove pitch: 0.3mm. Focal length: 300mm. Magnification: 3X or a 300% increase. Clean with a lint-free cloth. Mild soap and water can be used. Note: As with any magnifying sheet, these lenses need to be elevated at least several inches above the page in order to magnify. They do not provide any magnification effect if laid directly on the surface you are magnifying.