This pocket size watchmaker loupe has distortion free lenses. The shape of this eye loupe allows it to rest comfortably in the eye socket for hands-free use. It has a single ground and polished lens set in a lightweight black plastic frame. This Watchmakers Loupe magnifier has a 22 mm lens diameter and 33 mm diameter eye-piece opening. Made in India.
This is a single lens magnifier. The higher the magnification, the closer the focal length and the smaller the field of view. That means as you increase the magnification power, you move closer to your work and you will have a smaller area in focus. A 10X loupe will have the highest magnification with the closest focal length and the smallest "field of view" which means area in focus. A 3X loupe will have the lowest magnification with the furthest focal length and the largest field of view or area in focus.