In my opinion you have the best make of petrol equipment made, i strongly disagree with the frist answer that say's Robin, Robin is a throw away brand i should think they work perfectly well but when they break thats it throw it away and buy another....
They do make a blade for the weed-eater but it's for the high end models or professional models. So if it's a lower end model then it may not work, check with your local Stihl dealer. http://stihlusa.com
I don't know that model number, but Stihl makes the best. Mine is over 20 years old, and still sawing.