Ace makes a wide variety of filters available that work in combination to provide the best possible filtration for your work application. Generally speaking, 95% main filters and standard pre-filters provide effective filtration for the vast majority of welding operations. HEPA main filters can be used in place of a 95% filter to provide additional protection against toxic particulate such as Hexavalent Chromium. Specialty pre filters may be used to help abate smoke odors and oil mist. Your Ace dealer can you help determine the best combination of filters for your application.