Compared to the original springs, this product maintains the same feel when pressed while improving the responsiveness of the return and reducing vertical spring wobble after the valve has fully returned, allowing for more precise valve positioning. The following characteristics also change during performance: * Easier to hit high notes * Increased resonance (richness) in the mid to low range * Reduced stress on piston operation This product is the lightest, extra-light version, so the feel when pressed is lighter than the original. However, it makes it easier to hit the notes, and you can hit the notes with a light feel. It is used by attaching it to the back of the piston, so it can be used stably. The usage situation is that it has been hardly used.