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. 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 lightweight, it is easy to store and carry. Suitable for folk guitar, acoustic guitar, electric guitar, etc. Specifications: Material: Plastic + Metal Color: White, Orange (optional) Winding Speed: Max. 150KHZ Overcharge Protection 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 * 100mm / 4.72 * 3.94in Package Weight: 250g / 8.82ounces Package Size: 150 * 120 * 40mm / 5.91 * 4.72 * 1.57in Packing List: 1 * String Winder 1 * USB Cable