FREEDOM TO MOVE. Twixt Active Seating Chair, Extended-Height promotes small movements throughout the day, helping engage your major muscle groups to support better posture and balance. ERGONOMIC SUPPORT. The patented, flexible ring under chair base lets you adjust the angle of the seat to perch, lean or sit, encouraging a more ergonomic, truly one-of-a-kind experience. HEIGHT-ADJUSTABLE. Easy-to-reach ring right under seat controls the pneumatic height adjustment to match your current work surface. Upholstered seat swivels 360 degrees on an aluminum base for effortless movement.