Filters compressor air to provide Grade-D quality air for a specific number of workers. First stage element filters bulk water and particulate. Second stage coalescing filter removes atomized oils and ultra-fine particulates. Third stage removes organic vapors and odors. Filter change indicators are standard on all three filtration stages. Built-in CO monitor operates on twin 9 VDC, 115 VAC or 8-16 VDC for continuous detection. High-intensity audible alarm and light signals a high CO content in breathing air. Made in USA.