Battery Specification: 3.7 V 18500 LI-ION , Battery capacity. 2000 mAh Dimensions(Ø * L): 22-34*138 mm Weight: 195 grams(Pen with battery) Support work time : 7.0hour-9.0hour (Test Results) CHarging time :2-2.5hour 0.1V level control 5.0V-11.0V , Voltage output 5.0V-11.0V Recommended working voltage 5.5V-7.5V Nominal Voltage 12V , Nominal Torque 6.18mNM NO-load Speed 11000rpm , DC-motor Swiss motor Max. efficiency 85% ,Vibration value <2.5m2/s Replaceable Stroke 4.0MM ,Needle depth: 0-4.5 mm Overload and short circuit prompt