A wholly original replenishable carbon filter designed to permanently replace standard duct filters. This iF Award-winning patented structure can be regularly refilled to offer a cost-effective and sustainable solution for unwanted odors in your grow tent. The charcoal fan filter kit also includes 1+ refill, making it as efficient as two standard inline carbon filters while proving more affordable. You can purchase additional refills at a fraction of the price of an entirely new carbon scrubber to further increase the value of this kit. Features an expanded chamber that enables you to achieve factory carbon compression and the same lab-tested levels of odor-blocking effectiveness as standard carbon filters. This also eliminates the need for you to actively compress your replacement charcoal and facilitates the refilling process.