Description: MS 291 is built around one of our new fuel-saving engines with longer run times and lower emissions. And with an advanced pre-separation air filtration system, your air filter can last up to five times longer. Another great feature is an advanced anti-vibration system to reduce user fatigue. STIHL engineering is to thank for this high-powered, high-tech, low-maintenance chainsaw. It is truly a force to be reckoned with.