HVM-3 Binocular Headband Magnifier Visor with 2.5x and 8" Focal Length working distance. Headband is lightweight durable impact resistant visor shell fully adjustable to fit any size quickly and easily Headband is adjustable +/- 60 degrees either way The standard model does not have a glass lens nor the metal hinge construction, the 2.5x acrylic prismatic lens gives you an versatile & comfortable working distance of 8" or 203mm ideal for most repetitive applications and most tasks that require a hands free magnified view. Can be worn over eyeglasses and most safety glasses. 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. If you currently have a Donegan Optivisor all of your lenses and accessories & parts will fit this model.