With the touch of a button, you can change the fuel type (super premium, premium, standard pellets, utility pellets, or alternative fuels) from wood pellets, corn, wheat, barley, or paper pellets to all-bark pellets. The M55 features a low-maintenance burner. This patent-pending technology has an agitator rod in the burn pot that breaks up any clinker or ash and helps move it into the ash pan. This greatly reduces cleaning intervals and also allows you to burn lower-quality, inexpensive pellets and alternative fuels. The stove is EPA tested to 79.8-percent efficiency. Contact: www.enviro.com.