The Pentax 8x42 DCF CS Binocular is waterproof and nitrogen-filled (JIS Class 6) to handle the most extreme weather conditions (submersible to 1m). Phase coated roof prisms provide high resolution, high contrast images. Silver-deposited roof prisms reflect more light through the prism for a brighter image. Fully-multi-coated optics provide the maximum light transmission and reduced internal reflections. Inner-focus optical design allows improved sealing and improves balance. Fiber-reinforced polycarbonate for strength and rigidity. Full rubber housing protects the binoculars from shock and makes them easier to hold. Center diopter ring with click stops is easy to access and holds the adjustment firmly. Long eye relief for comfortable viewing with or without glasses. Helicoid eyepieces with four click stops allow you to properly set the eye relief. Compact size 5.6" and 5.8" for maximum comfort in field use.