A filter insert piece has a filter element with first and second pleated sections each having parallel pleats. The first and second pleated sections each have an inflow side. A first flat outflow side of the first pleated section and a second flat outflow side of the second pleated section adjoin a common clean chamber of the filter element. A length of the pleats of the first and second pleated sections is such that a spacing of an outwardly positioned pleat end face of the pleats at the first or second inflow side, respectively, relative to the center axis increases or decreases monotonic from pleat to pleat. The respective end pleats of the first and of the second pleated sections have a different length extension measured from the outwardly positioned pleat end face of the first end pleats or the second end pleats relative to the center axis.