1. Only one CR2032 battery is needed for power supply, no external power supply is needed, and it is free from the of power cord, which further reduces the dependence on desktop space and broadens the use scenarios. CR2032 is a very commonly used battery model, which can be easily bought in any supermarket or even canteen. A battery can last for several months, saving energy and protecting the environment. 2. When operating, not only the buzzer ring, but also the green LED light light up with the rhythm, and the sound and light follow, so that the rhythm can be easily controlled. For beginners, whether they follow the recording practice or the newspaper by themselves, the double prompts of hearing and vision are helpful to deepen the understanding of rhythm, correct the mistakes in techniques in time and prevent them from practicing QSD (bad hands). 3. For the old hand, daily practice can not only no longer rely on larger radio stations or traditional exercisers, but also visualize their own rhythm. CW is a language art as well as a music art. Everyone's rhythm has a personal style, and the rhythm style of everyone is more pleasing to the eye after being visualized by eye-catching green LED lights. 4. Manual keys supporting vertical operation, sweeping keys and mechanical semi-automatic keys for horizontal left and right operation, and other forms of manual electric keys are all integrated, without compromising any manual electric keys, and no matter what operation mode, they can be easily mastered with the help of this exerciser. Product name:manual key trainer Color:Black & White Material:PCB+Metal Package Contents: 1 * Practice Board 1 * Adapter 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.