This is a design for a high-end fountain pen, featuring a shape that gradually narrows from the connection between the middle cap and the pen body towards both the nib and the tail. During use, the increase or decrease of ink inside affects the overall balance of the pen, causing it to tilt either towards the nib or the tail, subtly reminding the user to refill the ink. When the ink is relatively full, the pen's center of gravity shifts backward, causing the barrel to rest on the desk while the nib rises; conversely, when the ink is low, the center of gravity shifts forward, making the cap touch the desk while the tail lifts. This method of reminder is both vivid and direct, yet subtle enough that those around the user may not notice it, allowing the message to be communicated smoothly.