1. Initiate 5 key structure with high practicability; 2. Precision structure design avoid greatly the damage of keys; 3. Pure copper nut and screw inner design improve greatly fluency of operating on condition of meeting the need of adjustable force faster more accurate and firm in the same way the section of strength is visible you can know better the condition of strength; 4. MFX5 unique save button function little finger strength training can be more compatible perfectly and firm; 5. It has good consolidate and strengthen function to playing skills of musicians such as guitarist and pianist it improve the strength and accuracy of fingers.