I say it on TBN everytime string trimmers come up. If you're going to be working with one for any more than about 30 minutes, get yourself one of these and adjust it right for your body and trimmer. Your back will thank you for days and days.
Amazon.com : HIPA 4119 71 9 1 String Trimmer Full Harness for STIHL FS, KM Series String Trimmer : Garden & Outdoor
Amazon.com : HIPA 4119 71 9 1 String Trimmer Full Harness for STIHL FS, KM Series String Trimmer : Garden & Outdoor