The seat has a base section (18) with upward projecting column (20) and a seat part (12), suspended from the column by a spring unit (22). The column has a mounting box (46) with a height-adjustable mounting part (36). This is fixed to box and column by a releasable locking unit. The spring unit has a two end sections (24,26), and the first one is fastened to the mounting part. The column has a row of snap-in holes (52) on the side facing the mounting box. The mounting box has at least one hole (50), which may be aligned with those in the column. The locking unit has a lever loaded by a spring.
