Whiteside Manufacturing Round Adjustable Seat (GRSRB) Seat pad is 12 inch with durable vinyl covering that can be cleaned easily Steel cast collars at the base of the seat and base of the cylinder add strength to the unit The gas filled cylinder adjusts from 16 inch to 20.5 inch in height Seat has five 2-1/2 inch oil-resistant rollers Ground clearance: 2-1/2 inch