Eschenbach's laboCLIP system is attached to the users spectacles to provide individual hands free magnification, it features: Comfortable working distance even with a high level of magnification Used with distance spectacles to achieve optimum image quality Lenses easily interchangeable, customer can use different lenses depending on task or changing needs over time Planoconvex or aspheric PXM lightweight lens for a distortion-free image with edge-to-edge sharpness Lens size: binocular - 74.5 X 22.5 mm, monocular - 40 mm Lightweight Lens clamp made from glass fibre reinforced plastic Ideal for both work and craft activities Supplied in a protective box Lens With Clip Varients Lens Magnification Working Distance Approx. 164617 Binocular 1.7 X / 2.5 dp 400 mm 164625 Binocular 2.5 X / 5.0 dpt 180 mm Lens Alone Varients Lens Magnification Working Distance Approx. 16455 Binocular 1.7 X / 2.5 dpt 400 mm 16451 Binocular 2.0 X / 2.5 dpt 250 mm 16452 Binocular 2.5 X / 5.0 dpt 180 mm 16453 Binocular 3.0 X / 7.75 dpt 130 mm 16454 Monocular 4.0 X / 16 dpt 55 mm 16457 Monocular 7.0 X / 28 dpt 32 mm Recommended use: Crafts, hobbies and occupational tasks that require hands-free magnification.