For the Synergy S40P model this filter set traps dust and dander particles with a thick pleated HEPA media filter captures odors with a granulated charcoal filter and protects the direct air motor from debris with a direct air motor filter. This filter set will not fit the X9 or G9 models. See part SF9UG-1 SF9G-1 SF9U-1 or SF9-1 instead.