Ergonomic Kneeling Posture Task Chair w/ Back & Wheels Seat Size: 17''W x 13''D. Seat Height: 20 - 24''H Back Size: 15.5''W x 17.5''H Overall Dimension: 26''W x 31''D x 38 - 42''H. Weight Capacity: 250 lbs. Knee Rest: 15.5''W x 11.5''D x 2.5''T