... .2. Piston Type :1 Steel-insert piston , 2 ALFIN piston , 3 Cast Iron piston , 4 Cooling channel piston , 5 One piece casting piston , 6 Compages piston , 7 Forged piston3. Piston ... -insert piston , 2 ALFIN piston , 3 Cast Iron piston , 4 Cooling channel piston , 5 One piece casting piston , 6 Compages piston , 7 Forged piston piston, 8 Two pieces piston/Double ...