Specifications: Type: Prism Binoculars Magnification: 18x Objective Lens Effective Diameter: 50mm Filter Size: 58mm Real Field of View: 3.7° Apparent Field of View: 66.6° Objective Lens Construction: 4 elements in 3 groups (including protective glass) Eyepiece Lens Construction: 7 elements in 5 groups Exit Pupil Diameter: 2.8mm Eye Relief: 15mm Prism