Vortex Optics Razor HD Roof Prism Binoculars 10x magnification and 50mm objectives lenses, the Razor HD features hand selected prisms and premium high density glass, delivering unparalled resolution and color, creating stunning high def images. State of the art anti-reflective coatings with cutting edge plasma tech application guarantee the highest level of brightness during critical low light periods. The true open hinge magnesium chasis forms a strong, lightweight, and ergonomic design resulting in more durability in the field. Strategically placed indents in the rugged armor ensure a comfortable grip in any conditions. Adjust the multi-position eyecups to optimize fit for comfortable viewing with or without glasses. A locking right eye diopter adjusts for focal differences between your eyes. Argon purging and o-ring seals provide a lifetime of waterproof and fogproof performance. Ultra-hard, scratch resistant armortek protects the exterior lenses from scratches, oil, and dirt. Close your right eye or cover the right objective lens with your hand. Look at the object with your left eye and adjust the center focus dial until the image is in focus. Close your left eye or cover the left objective lens with your hand and rotate the ring until the object is in focus. Blow away any dust or grit before wiping the lens. Use a can of pressurized air, soft camel hair brush, or acrylic optical brush. Gently remove smudges, fingerprints, and eyelash oil from the lens. Use a small amount of water or your breath to moisten the lens then wipe away smudges with a clean lens cloth. Isopropyl alcohol can help remove marks like fingerprints.