The Nikon Prostaff 3S features an optical system created from lead- and arsenic-free Eco-Glass. Specially coated roof prisms and antireflection multicoated optics produce bright, high-contrast images with true color. Specs Magnification: 10x. Objective lens diameter: 42 mm. Field of view: 367 ft. at 1,000 yd. Eye relief: 15.7 mm. Dimensions: 5.9"L x 5.1"W x 2.0"H. Weight: 20.3 oz. Construction Durable reinforced polycarbonate resin chassis protected by black rubberized armor. Silver-alloy mirror coating on the mirror surfaces of the prisms for a bright and clear view. Nitrogen-filled and O-ring sealed for water and fogproof performance. Twist-up rubber eyecups for use with or without eyewear. Additional Features High-eyepoint design for long eye relief without vignetting, even when you are wearing eyeglasses. Textured, nonslip grip. Imported.