The Lytzen class 10,000 Dry Heat Sterilizer is without internal HEPA-filters.
Only HEPA-filters on the air inlet and exhaust are necessary. The chamber construction and the sealing of the chamber guarantee, that class 10,000 can be obtained throughout the complete cycle - without the use of internal HEPA-filters. As it can be seen from the particle report (to the right), Lytzen sterilizers are actually far below the class 10,000 limit.
The absence of internal filters reduces the overall price for the sterilizer considerably.