Ergonomic Multi Function Drafting Office Stool (Adjustable - 26'' - 30.5''H or 22.5'' - 27''H), Black Seat Size: 18''W x 16.5''D Seat Height: 26'' - 30.5''H or 22.5'' - 27''H Back Size: 16''W x 16.5''H Overall Dimensions: 20''W x 20''D x 38.25'' - 42.75''H or 42.25'' - 46.75''H