The MS 261 C-M has all the same great features as the MS 261—low exhaust emissions, high fuel efficiency and robust performance—but also features the advanced STIHL M-Tronic™ engine management system. The STIHL M-Tronic™ onboard microprocessor digitally monitors and automatically compensates for changes in your work conditions, including elevation, temperature, fuel quality, varying octane levels, and dirty filters. The end result is maximum performance across a wide range of cutting conditions without making any manual adjustments. The MS 261 C-M also features redesigned cylinders and a slimmer, ergonomic housing for an impressive power-to-weight ratio.