Vortex Optics Kaibab HD Binoculars 15x magnification and 56mm objective lenses, when serious patience and superior optics are required to locate tough to spot game at extreme distances, the Kaibab HD gets the job done with premium quality, high-powered optical performance. The APO optical system features premium, high density, extra-low dispersion lenses that provide long range clarity. Lenses are fully multi-coated with XR plus anti-reflective coating, that deliver exceptional light transmission and color accurate views. The Kaibab HD is covered in durable, non-slip rubber armor and ultra-hard armortek lens coatings to protect your binoculars from the most rugged environments. The focus wheel operates with a slow, fine control giving you smooth and precise image acquisition. A right eye diopter locks down to keep the binoculars optimally focused. Multi-position eyecups twist up and down for customized eye relief. Argon purging and o-ring seals ensure the Kaibab HD is both waterproof and fogproof. 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.