The pre-filter removes coarse particles, such as dust, thus extending the life of the main filter. The main filter provides the greatest amount of surface area within the volume of the filter case. The standard filters contain an activated carbon element built into the filter. This filter is designed to last the life of the main filter. The carbon odor filter is designed when the primary use of the system is to remove odors created by various processes. Its pleated media contains highly activated carbon and provides a greater gas absorption area compared to the activated carbon portion of the standard main filter that comes with the Hakko FA-430 Fume Extraction System.