Element Optics 10x42mm Helix HD Binoculars BAK-4 Magnesium. An advanced optical system featuring ED glass provides stunning clarity and is housed in a rugged rubber-coated chassis built to take the inevitable knocks that come with the territory. Specifications for Element Optics 10x42mm Helix HD Binoculars: Manufacturer: Element Optics Color: Green Magnification: 10 x Objective Lens Diameter: 42 mm Prism Material: BAK-4 Eye Relief: 15.2 mm Exit Pupil: 4.3 mm Field of View Linear: 341 ft at 1000 yds Length: 5.58 in Weight: 22.9 oz Last Chance: Yes Package Contents: Element Optics 10x42mm Helix HD Binoculars Bino case and harness Lens cloth Product manual Element Optics 50091: 10x42mm Element Optics Helix HD Binoculars BAK-4 Magnesium