The Stihl Piston Cylinder Diameter 42.5 mm (code 1143-020-1205) is an original spare part for Stihl MS 231 chainsaws. Includes piston Diameter 42.5 mm, compression ring Diameter 42.5x1.2 mm, piston pin 10x8x27.88, snap ring 10, screw for plastic IS-D5.3x43. MN