Purolator's ULTRA-CELL HEPA filter products are high efficiency aluminum separator style filters, except for the ULTRA-CELL "V" Pleat. They are manufactured for environments requiring 95% minimum efficiency on .3 micron particles, 99.97% efficiency on .3 micron, or 99.99% efficiency on .3 micron (scan tested to assure no leak shall exceed 0.01% of the upstream challenge).