Hardly used. From the homepage: Modern people spend a lot of time in a seated position, such as at a desk, reading, doing housework, childcare, eating, playing games, and using smartphones, which causes the muscles on the front of the body to constantly contract. The "Miodre-style Just-Lie-Down Stretch Pillow" allows you to stretch those contracted front muscles simply by lying down. No other actions or exercises are necessary. It's a product that allows you to easily stretch just by lying down for only 10 minutes, twice a day, upon waking and before bed. The front muscles refer to the three muscles that tend to contract the most in daily life (pectoralis major, rectus abdominis, and iliopsoas). When the pectoralis major becomes stiff, the chest sags; when the rectus abdominis becomes stiff, the stomach protrudes; and when the iliopsoas becomes stiff, the buttocks sag. By stretching the pectoralis major, rectus abdominis, and iliopsoas, the muscle balance between the front and back of the body is improved, flexibility increases, posture improves, and gait is also improved, making it possible to aim for both health and improved style.