HEPA (High Efficiency Particulate Air) filtration is typically used in hospitals, medical facilities, and research facilities that require extreme sterility. HEPA filters are able to trap 99.97 percent of particles that are 0.3 microns or larger. 
HEPA filters can also be used for Mycology to provide a clean, uninterrupted stream of highly filtered air which is necessary for many Mycology tasks like culture isolation, culture propagation, inoculation, and building fruiting trays.
This Astrocel filter is composed of interlaced glass fibers that are twisted and turned in myriad directions to create a fibrous maze, and is the most efficient HEPA air filter commercially available.
 
SPECIFICATIONS
Dimensions - 48" x 24" x 5 7/8" (121.9cm x 60.9cm x 14.8cm)
Filtration - 99.99% efficient on particles 0.3 micron & larger
Resistance - At 2000 CFM this filter has an initial resistance of 1.0” In W.G.