HVM-4 2.5xl Is the same as our HVM-4 Premium Binocular Headband Magnifier Visor but with 2.5x and 8″ Focal Length and 5x swivel eye loupe that adds extra magnification for one eye very close up inspection and detail work. Fully adjustable to fit any size quickly and easily.Headband is adjustable +/- 60% either way The 2.5x glass prismatic lens gives you an close working distance of 8″ for most repetitive applications and hands free magnified view. 2.5x is the highest magnification for binocular (both eyes) magnified view, anything beyond 2.5x and the focal length is too close to see with both eyes. Can be worn over eyeglasses and many safety glasses Lens is 6 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.