Donegan DA-10 Optivisor Headband Magnifier, 3.5x Magnification, 4 Focal Length Black

Headband Binocular Visor With Snap-in 3.5x Magnifying Lens Plate For Hands-free Viewingground And Polished Glass Prismatic Lens For Improved Focus And Reduced Eye Strainvisor Size-adjustment Knobs For Customized Fitvisor Tilts Out Of Way When Not Needed4' Focal Length For A Variety Of Uses The Donegan Optivisor Is A Hands-free, Headband Binocular Magnifier That Has Optical Glass Lenses That Are Ground And Polished Into Prismatic Lenses For Quality And Clarity, And Is Available In Multiple Dioptric Strengths (indicated By The Number In The Model) Which Provide Specific Magnification Power (x) At Specific Focal Lengths, Or Distance From Object. This Magnifier Enhances The Size And Resolution Of An Object Or Image, And Is Commonly Used For A Variety Of Applications Such As Jewelry-making, Watch- Making, Needlework, Artwork, Electronic Inspection, Book-reading, Print Inspection, And Stamp-collecting. The Optivisor Magnifier Features Replaceable Binocular Lenses That Have Beveled Edges That Are Mounted In An Interchangeable Plastic Frame. An Adjustable Headband With Padded Leather Comfort Band Conforms To A Variety Of Head Sizes And Provides Comfort For Hours Of Continuous Use. It Can Be Worn Over Prescription Or Safety Eyeglasses. A Durable, Plastic Visor Tips Up Above The Forehead When Not In Use. Spring-loaded Pivot Screws Hold The Headband In A Raised Or A Forward-facing Position. The Magnifier Weighs 0.67 Lbs. Diopter (d) Is A Technical Term For The Measurement Of The Light Curvature And Thickness Of A Lens. 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”). See The Magnification Chart. The Higher The Diopter, The More Magnification A Lens Can Provide. As Magnification Increases, Distance To The Object (focal Length), And Field Of View (diameter, Or Narrowness Of View) Decreases. Magnifiers And Prescription Eyeglasses Have A Diopter Value, Such As 1.5 Or 2.