Optivisor Additional Lens Plates. DA-2 Lens Plate 1.5x magnification 51cm/20'' working distance. DA-3 Lens Plate 1.75x magnification 36cm/14'' working distance. DA-4 Lens Plate 2x magnification 25cm/10'' working distance. DA-5 Lens Plate 2.5x magnification 20cm/8'' working distance. DA-7 Lens Plate 2.75x magnification 15cm/6'' working distance. DA-10 Lens Plate 3.5x magnification 10cm/4'' working distance.