The BOSCH VF430H HEPA filter captures 99. 97% of particles 0. 3 microns and larger. This filter is designed for use with BOSCH gas20-17a 300-cfm dust extractor. The filter has a low-stick surface to enhance the filter-cleaning process. This filter can help users move toward compliance with OSHA respirable crystalline silica dust regulations. The VF430H Filter and dust extractor unit is a critical component in the end-to-end BOSCH PRO+GUARD protection system – along with the right tool, accessory, attachment, connections and respirator. The use of a filter bag is highly recommended When using VF430H, As it will help prevent the filter from being directly exposed to abrasive materials and sharp objects that can be collected during normal use of a dust extractor. It is for dry use only and will be damaged by wet-vacuuming.