The lens of our binoculars is designed with multiple coatings that increase light transmission in the dim light of dusk and dawn, and multiple anti - reflective coatings on all glass surfaces exposed to air. The Chaku binoculars are sealed with rubber O- ring to prevent the ingress of moisture, dust and dirt so they are 100 % waterproof. The binoculars are filled with nitrogen gas to reduce the risk of blurred when used in areas of high humidity or sudden temperature changes. The exterior of the Chaku binoculars is coated with a durable rubber armor and provides a firm surface to hold even when wet. Chaku binoculars offers high quality at a reasonable price.