The WS15 is a great choice because of its unique base and seat tilting feature which make the WS15 a perfect choice for sit/stand applications. Sit or stand ?dual positioning. Ergonomically designed to support you while you work. Move effortlessly from sitting to standing to leaning back. Sit/Stand Stool lets you sit while standing and alleviates stress points on lower back. Seat tilts up to 20 degrees. A workstool that works for you all day long.