Celestron 71018 SkyMaster 20x80mm Porro Prism Binoculars with Multi-Coated Lens, BaK-4 Prism Glass and Carry Case, Black. SkyMaster 20x80 mm Porro Binocular. BRIGHT, SHARP VIEWS WITH BaK-4 PRISMS: The SkyMaster is a favorite among those who view in dim conditions near dawn and dusk or at night for astronomy.
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