Binocular headband magnifier provides hands-free magnification and viewing for a variety of applications such as jewelry-making, watch-making, needlework, artwork, electronic inspection, book-reading, print inspection, and stamp-collecting Includes 4 lenses in multiple dioptric strengths that provide a specific magnification power (X), depending on the distance from the object Optical glass lenses are ground and polished into prismatic lenses for quality and clarity; easier to clean than acrylic lenses .A dioptric number and a magnification number are not the same thing. Diopter strength represents a specific magnification power (X). For example, a 5-diopter provides 2.5X magnification (at a distance of 8"). Can be worn over prescription or safety eyeglasses. Includes #2, 3, 5, 7 diopter lenses.