Used for about two weeks. Purchased at Tokyu Hands. About this product (quoted from Amazon) * Guides the pelvis to the optimal angle, reducing the burden on the lower back and back. The "lever principle" causes the front to sink and the rear to rise when sitting. * Reduces the burden on the lower back. "Cradle structure" that does not fix the pelvis. US and Japanese patents obtained. Patent number 5502901. * Mesh fabric for excellent breathability. Easy to sit on and less tiring. Twice the cushioning of conventional products. \*Compared to our products, such as the Release Grip. Heat-resistant and ideal for cars. * Large hole to prevent tailbone compression. Guide cup to prevent slipping forward. Easy to carry with the hook on the back (hook only for regular size). * Shape that fits the pelvis and buttocks for improved hold!