HVM-4 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. The HVM-4 premium features an aluminum alloy headband pivot mechanism as well as scratch resistant glass prismatic lenses, more suitable for the industrial environments. The 1.5x lens gives you an versatile and comfortable working distance / focal length of 20″ is ideal for most applications. Can be worn over glasses. Lens is 2 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