The Weller 0058735838 Compact H13 HEPA-Gas Filter is designed for use with Zero Smog 6V, WFE4S and WFE20D Fume Extractors. It consists of a H13 HEPA filter and a wide band gas filter. The wide band gas filter is 50% active carbon and 50% Puratex, while the H13 HEPA removes 99.75% of particles up to 0.5 micrometers.