Stihl does not list a part number for only the Cylinder, and you can't buy just the cylinder from them - the number for a cylinder includes the piston/rings/pin. Stihl says they "match Piston and Cylinder for fit" and that's why they only sell them as a set. Hmmm...
044 - 1128 020 1227 and the older version - 1128 020 1201
046 - 1128 020 1221, and the older version - 1128 020 1217