Nispira VF3500 Vacuum Filter for Ridgid Wet/Dry Vac 3-Layer Filters WD4050 WD4070 WD4522. As fine dust and particles are easily drawn into these powerful machines, a reliable filter is needed to trap 99.97% of airbrone particle 0.3 microns in size. This HEPA filter fits a wide range of DeWalt wet/dry vacuums between 3 to 4.5 gallons in capacity, keeping them performing at their best. Whether tackling dust from construction jobs or cleaning up after projects at home, this filter will keep your vacuum functioning properly without clogs. Changing filters regularly helps vacuum and air intake performance while protecting indoor air quality - this affordable and highly-rated Nispira filter delivers on all counts.