Details:
 1. Price include:
 1pcs pen
 1pcs USB line
 2. Japanese engine
 Motor: 4 W
 Material: Aircraft aluminum
 Frequency: 0-11000RPM
 Working volt: 4-12V DC
 Stroke: 4.2mm
 Charging voltage: 5V / 1A
 Charging time: 3 hours
 Usege time: 5-8 hours