What type of spark plug is used in a MAC 1385l gas trimmer?

I bought a used MAC 1385l string/gas powered weed trimmer. I had the guy start it up for me and it worked fine. Same old story, got home and it wouldn't work. Someone suggested replacing the spark plug. I took the spark plug with me and attempted to replace it, 3 different hardware stores did not carry it. Eventually, I lost the spark plug, and of course I have no idea what kind it was. Can you help me?