anything by the weedeater name is made by poulan, could be something old, most of the new ones are only 2 springs on the muffler, in the old ones there were several sizes out there, anything from 21 to 32cc, measure the bore and stroke and make a calculation... bore you can in most cases with a digital caliper through the exhaust port, stroke with a digital caliper through the spark plug hole then the old formula pi*bore*bore*stroke/4 (the 4 is because I used the bore instead of the radius of the cylinder)