The Stihl 11391209702 Pump Piston Set is a genuine OEM replacement part designed for the oil pump system of numerous Stihl MS and MSE series chainsaws. This essential component ensures proper lubrication for optimal saw performance and longevity. It is compatible with models including MS211, MS211 C, MS231, MS231 C, MS241 C, MS251, MS251 C, MS261, MS261 C, MS271, MS271 C, MS291, MS291 C, MS311, MS341, MS361, MS361 C, MS362, MS362 C, MS391, MS441, MS441 C, MS461, MS661 C, MS880, MSE210 C, and MSE230 C.