HEPA or ULPA filters of >99.99%@0.3um are made of microglass. As such if they are not in the carton, they are very fragile, only hold them by the frame and avoid touching the faceguard or filter media. Any slight damage or mishandling will render the HEPA filter to leak. Please see guide below
Installation Guide and Manual for
HEPA DTM and RPM and FFU