The scrubber canister contains the scrubbing media that removes CO2 from the breathing loop. The Optima CM uses an axial style scrubber canister and can be used with either Micropore ExtendAir cartridges or loose packable CO2 absorbent.
Assembly is slightly different depending on which scrubber media is used. The wave spring and top plate with screen are not used when using an Extendair cartridge. The finger nut is reversible. It is used in one direction when packing loose CO2 absorbent and is flipped over when using Extendair cartridges. See the How to Pack the Scrubber section for more information on properly seting up the scrubber canister.