What is in the set
Blueair's combined particle and carbon cartridge for the Blue Pure 311i Max: the HEPASilent particle stage and an activated carbon layer for light household odours, bonded into one piece that you replace as a unit.
Blueair does not state that any part of it is washable, and the machine's own page describes "4 layers of filtration" without naming them individually, so what the four layers are is not documented on either page.
Filter life is not a fixed calendar interval on this machine. Blueair's RealTrack algorithm counts fan speed, running time and measured pollution, and the stated result is up to nine months.