The Air Box 3 706106 Special Edition charcoal filter system has 8-inch flanges and a max CFM of 1200 for scrubbing and a recommended CFM of 600 for exhausting. These units are completely airtight and easy to install, use, and maintain as they fit into any ducting or filtering system. Made with 100 percent premium virgin coconut charcoal, it features replaceable high-flow filters which use 100 percent of the available surface area, for optimum performance. Great for commercial or residential use. One pre-filter and three charcoal filter cartridges included.