STIHL MS 261 C-M Gas Chainsaw (50.2cc) M-Tronic - 18"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