Principle:In order to see the details of a small object, it is necessary to move the object to the eye, so as to increase the of and form a larger on the retina. when the object is too to the eye, it can not see clearly. In other words, to be aware of , not should the object have a good enough to the eye, also should take the appropriate distance. Obviouy, for the eyes, these two requirements are mutually restrictive. If a convex lens is placed in the front of the eyes, this problem can be solved.Convex lens is the simplest magnify glass, which is a simple optical instrument to help the eyes observe Small objects or details.Magnification: 10XColour:blackMaterial:plasticSize:41 x 44 x 45mmLens diameter: 20mm Contents:1 x Scale magnifier the above content, other are not included.Note: Light and different displays may the color of the item in the a little different from the real th. The measurement allowed error is +/- 1-3cm.