The AC 4 Office Chair was designed by Antonio Citterio for Vitra. This office chair integrates ergonomic properties in such a subtle way that the constructional tricks are hidden away, creating a balance between advanced ergonomic functionality and aesthetic design. The synchronised mechanism of the Vitra AC4 comes with an automatic initial setting of the backrest tension to the user’s weight and provides seat height adjustment as standard.The innovative technology is not showy, being hidden under foam padding. This makes the Vitra AC 4 an iconic object with an aura of elegance and beauty.