100x180 Zoom Binoculars Day Night Vision Bak4 Prism High Power Waterproof and CaseMagnification: 10-180xObjective Lens Diameter: 50mm (Broadband green or blue mode)Eyepiece Diameter: 17mmField of view: 235FT/1000YDS; 78M/1000MPrisma: bak4Waterproof: Lens barrel filling the high-purity nitrogen, waterproof and mouldproof, will not be affected by daily use in the rain or with damp.The internal and external material: Metal lens barrel, rubber outsourcing, exquisite and comfortable feeling, elegant appearance, fine workmanship, convenient to useFocusing type: Central Axial plus right eyepiece fine-tuning, can focus focal distanceCoating: Several layers of vacuum high light transmittance green film, powerful light transmittance performance and high definitionApplication: bird appreciation, watching sports game or the concert, outdoor travelling, enjoying the prospect etcTelescope Maintenance Method:After purchasing a telescope, you must pay attention when using it: Its storage place must be dry, since the film is easy to fall off and the prisma may be fogging or mouldy fter long-term becoming damp. When using, if it is found that there is some dirt or traces on the lens, DO NOT swab with waterThe best way is to use swab at home (cotton swab) and dip it in some alcohol or gasoline, wipe gently. Better not to use lens wiping cloth to dry clean, it is easy to scratch the lens surface.Note: This binoculars are light enhancing or glimmering Night Vision,it will not work in full dark environment.