It uses rechargeable lithium batteries,which are light in weight,long in life,more comfortable to carry,and suitable for various surgical operations. Magnification: 3.5X. Working distance: 420 mm. Portable headlamp is compact and lightweight It has a wide field of view and ample depth of field,as well as enough to meet daily operational needs. It is the most popular model among dental students,dental hygienists,and dentists. Used to reduce the fatigue of dentists' eyes,neck and shoulders caused by long-term work with their heads down.