Is a filter for biomass burning appliances, easy to install, easy to maintain, it reduces up to 90% emissions of particulate matter PM10 and PM2.5. I doesn’t obstruct the natural flue of the stove, and its design allows to reduce the burning speed of the firewood. How much? According to certified testings, around 20%. For optimal results, we always recommend the use of dry firewood, with less than 25% of humidity.