Bushnell H20 10 x 25 H20 Roof Prism Binocular Compact & Durable Waterproof Design Is O-Ring Sealed & Nitrogen-Purged For 100% Reliable, Fog-Free Performance Large Center Focus Knob For Easy, Precise Adjustments BaK-4 prisms for bright, clear, crisp viewing, multi-coated optics for superior light transmission 100% waterproof/ fogproof, O-ring sealed and nitrogen purged for reliable, fog-free performance Non-slip rubber armor absorbs shock while providing a firm grip Fold-down or twist-up eyecups Large center focus knob for easy, precise adjustments, Long eye relief