Freshen up your workspace with fresh Weller filters. The filters are the most critical part of the fume extraction units when it comes to the health of operators breathing workplace air.The HEPA particle filter and the granular gas filters are combined in such a way that they are replaced together as a main filter unit. With use, the HEPA clogs up and the gas media gets saturated and oxidised. The fine dust filter (pre-filter mat) is the preliminary stage of the filtration and is typically replaced as often as every month depending on the application.This filterset is a convenient way of replacing main filters and pre-filters in an optimal proportion.