Marathon 6x30mm BAK-4 Prism Binocular Black. Engineered with a premium BAK-4 prism it offers an excellent viewing experience with superior light transmission and less peripheral light being lost due to internal reflection. This binocular is built to thrive in any environment; waterproof and submersible to a depth of 0.5m for up to 20 minutes and featuring a nitrogen-filled case to prevent fogging of the lenses during changes in heat or humidity. This model is also shockproof designed to withstand sudden drops or extreme pressure. Specifications for Marathon 6x30mm BAK-4 Prism Binocular: Manufacturer: Marathon Color: Black Magnification: 6 x Objective Lens Diameter: 50 mm Prism Material: BAK-4 Eye Relief: 0.7 in Exit Pupil: 2.6 mm Field of View Linear: 488 ft at 1000 yds Optical Coating: Coated Weight: 1.65 lb Package Type: Box Package Contents: Marathon 6x30mm BAK-4 Prism Binocular Marathon BI030030: 6x30mm BAK-4 Prism Binocular Black