The Stihl ball bearing (code 9523-003-4301) is an original spare part to be mounted on the crankshaft of the Stihl MS270 MS270C MS271 MS271C MS280 MS280C MS291 MS291C chainsaws and Stihl BR350 BR430 BR450 blowers The Stihl bearing allows the rotation of the crankshaft, and consequently, the rise and fall of the connecting rod and piston MN