YOCTOSUN Head Wearing Watch Repair Magnifying Glass Double Eye LED Lighted Jeweler Glasses Magnifier 10x 15x 20x 25x Great for Mechanical processing, jewelry appraisal, watch repair and miniature engraving etc. Too high magnification is not suitable for reading books and soldering electronics. This watch repair magnifier is not suitable for person who has limited eyesight. 4 Pairs of replaceable lens included, with different magnifications (10X, 15X, 20X, 25X), can be interchanged quickly; If this magnifier is used for long time, you may use two lens barrels alternately to eliminate visual fatigue and improve work efficiency. Left right double eye patches magnifier loupe with adjustable LED to help work in low-light conditions ( three AAA Batteries Included). Its battery duration is twenty hours longer than that of old-style product with button batteries. Eye patches can be moved leftwards and rightwards, and can rotate 150 degrees upwards and downwards.  It can't use both of eyes lens (when you're working ) Short focal distance from lens to product is 0.2-2in (0.5-5cm), just like the principle of microscope. Bracket and headband is interchangeable to each other. It is advisable to choose lens barrels of appropriate magnification according to the size of the object to be observed.