Day/Night Vision 40x60 Zoom High Power BAK4 Monocular Telescope Waterproof. TIANYAN 40x60 binoculars, design with 12x powerful magnification, 42mm large objective lens,374ft/1000yds large field of view, and 6.5°angle of vision,adopts quality bak4 prism FMC Lens optics, which can help you delivers a larger image, ensures clearer details, brings the world closer to you, perfect for birds watching,hunting, concerts, and sports game,which is an essential helper for outdoor travel.