DESC: These binoculars are the first to combine the handling characteristics of a roof-prism binocular with the performance and price of a porro-prism design. The diopter adjustment lever has been ergonomically placed on the center focus wheel for fast, easy diopter adjustments. And no matter how bad the conditions may get, rest assured Acadia's will hold up because they are armored, waterproof and nitrogen-filled. Fully multicoated lenses provide enhanced photopic transmission, which ultimately give you a bright, crisp image.