Granite Binoculars feature ED glass in the optical design. They are also useful in lowlight situations helping you to pick out details in subjects in dense brush even at dawn and dusk. FULLY MULTI-COATED OPTICS AND BAK-4 PRISMS - The Phase Coated Prisms correct out-of-phase shifts of light rays to ensure maximum contrast while providing superb natural color fidelity and vivid color saturation.