Qauick GearBox Head Fits Stihl Chainsaw Stihl FS120 FS200 FS250 BRUSH Cutter Parts 4137 640 0100 New Aftermarket Gear Box Head Stihl Trimmer FS120 / FS200 / FS250 / FS120R / FS200R / FS250R Replace part numbers: 4137 640 0100 Pls check your correct replacement parts before purchase, the picture show more detail, thank you. Package Include: item as pictured