STIHL MOTOR SAW MOTOR SHAFT RETAINING RING MODELS: 028 , 030 , 031 , 032 , 038 , BR 320 , BR 340 BR 380 , BR 400 , BR 420 , FS 360 , FS 420 FS 500 , FS 550 , SR 320 , SR 340 , SR 400 , SR 420 MEASUREMENTS: OUTER DIAMETER: 22 mm INTERNAL DIAMETER: 13 mm WIDTH: 5 mm CODE: 40271858 ORIGINAL CODE: 9640 003 1600 MP