Product Code: 5850/15Description: Red VTM Clear ReaderMagnification: 1.7xLens Diameter: 50.5mmImage Vergence: -4.0DEffective Focal Length: 52.90mmField of View on Page: 143 x 104mm5850/15 (1.7x) VTM Clear Reader - BluePart No:5850/15 Technical SpecificationsDescription: Red VTM Clear Reader Magnification: 1.7x Lens Diameter: 50.5mm Image Vergence: -4.0D Effective Focal Length: 52.90mm Field of View on Page: 143 x 104mm