HVM-3 is a Headband Magnifier for professional and hobbyists it is fully adjustable to fit any size quickly and easily and is ideal for Watchmakers, jewelers, tool & die makers, engravers, stamp and coin collectors, needlepoint, physicians, dentists, pharmacies and hospitals. Headband is adjustable +/- 60% either way Our 1.75x lens gives you an versatile and comfortable working distance / focal length of 14″. Can be worn over glasses. Lens is 3 Diopters. Other lens magnifications available for purchase for the HVM-3 and HVM-4. Our standard size lenses will also fit many other headband magnifiers including OptiVISOR® Brand.