Product Code: 5850/12Description: Red Visual Tracking MagnifierMagnification: 1.7xLens Diameter: 50.5mmImage Vergence: -4.0DEffective Focal Length: 52.90mmField of View on Page: 143 x 104mm5850/12 (1.7x) Visual Tracking Magnifier - RedPart No:5850/12 Technical SpecificationsDescription: Red Visual Tracking Magnifier Magnification: 1.7x Lens Diameter: 50.5mm Image Vergence: -4.0D Effective Focal Length: 52.90mm Field of View on Page: 143 x 104mm