I tried inflating it and sitting on it once. It will be shipped deflated. The air pump in the image is not included with the product, and the box cannot be sent. Please be aware of this. ▼ Two-layer structure, top and bottom independent. Adjust the amount of air in the top and bottom layers to adjust the comfort and instability of the balance. The top layer is donut-shaped with a depression in the middle for stable sitting. The bottom layer sways when you sit on it, creating an unstable state. It's a compact size that fits on a chair. ▼ "While-doing training" for effective exercise. Perfect for training while watching TV or working. ▼ The swaying cushion creates an unstable state, constantly engaging your core muscles, and unknowingly training your core. By sitting while maintaining balance, muscles such as the abdominal and back muscles are strengthened, naturally maintaining good posture. Health equipment, exercise goods, diet, balance cushion