This is Nitori's round cushion, the "Office Cushion (Seamen O Bresa)". I purchased it for the regular price of 2,490 yen. I used it at the office for about a month, but I no longer need it, so I'm selling it. Please refrain from purchasing if you are sensitive to used items. It supports ideal posture and helps prevent lower back pain, etc. Your buttocks fit into the donut-shaped hole, and the front indentation fits your thighs. The back has a non-slip grip for stability. The cover is made of mesh material for good breathability. Also, it can be removed from the cushion and hand-washed.