A combination filter assembly having a plurality of filter sieves positioned in parallel one after the other in the direction of flow. The machine 10 has a machine body 14 and an arbor 18. The absorber maintains its shape through integration with the first seat cover via the first joining member. The outflow conduit is fluidly coupled to the pump to conduct blood between the pump and the patient. In the in-wheel motor system, the oil tank and the oil pump may be efficiently arranged to minimize the size of the oil tank and to improve the cooling performance. Regarding this difference in the density value, determination on whether or not density unevenness caused by the color mixing or the landing position deviation occurs is made by using a threshold value and a threshold value different from that.