Features: Easy to change the strings, clockwise or counterclockwise switch to control string tension. Easy to operate, saving time and effort. Built-in rechargeable li-ion battery, charge via included USB cable. Compact and , it is easy to store and carry. The electric string winder is easy to change the strings, easy to operate, saving time and effort. It is suitable for folk guitar, acoustic guitar, electric guitar, etc. Suitable for folk guitar, acoustic guitar, electric guitar, etc. Specifications: Winding Speed: Max. 150KHZ Overcharge conservation Voltage: 4.3V Working Voltage: 2.7-4.3V Battery: Li-ion 3.7V 800mah Working Speed: 5rpm/s Charge Time: 2-5h Item Size: 120 x 100mm / 4.72 x 3.94in Color: White Material: ABS Package Contents: 1 x Electric guitar string winder 1 x Charging cable Due to the lighting problem, there is a slight color difference Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.