STIHL engine technology means low fuel consumption, longer run times, and reduced exhaust emissions in this high-powered chainsaw. The MS 391 features STIHL engine technology that adds fuel efficiency while reducing exhaust emissions, as compared to other chainsaw models. Though equal in weight, the MS 391 is more powerful than the MS 311. Add to that an optimal power-to-weight ratio and you have a chainsaw that’s cut out for the big jobs in field, farm, and ranch. Felling trees, cutting firewood, and cleanup after the storm just got a whole lot easier with the rugged MS 391.