The Pentax 7x50 Marine Binocular has a built-in Compass, with an easy to read compass scale, on liquid bearing for quick dampening. Nitrogen-filled, waterproof construction of these Pentax 88039 Marine Binoculars allow them to be used in the most extreme weather conditions. High-resolution phase-coated and super-reflective coated BaK-4 roof prisms provide high resolution, high contrast images. Fully multi-coated lenses increase light transmission and color quality. External lens coating prevents the elements from obscuring your view. Rubber covered exterior of the Pentax 88039 Marine Binoculars provide a sure grip and protects the internal mechanisms from damage. Helicoid eyepiece ring gives the most comfortable eye relief. Inner-focus optical design adds to the durability.