Compatible with Stihl FS 38, FS 40, FS 55, improved handling. The high-quality sprocket helps improve the handling of the brush cutter's pivoting head, giving you better control and increasing gardening efficiency. Included clutch × 1, passive disc × 1.Perfect fit The clutch drum is designed and manufactured to strict standards. Perfect match with the original parts. Replacement is quick and easy. The sprocket has undergone rigorous testing to meet industry standards. Note: The data is all measured manually, please allow 1-3 cm error, due to the difference in light and temperature, there will be a certain color difference, the actual object received shall prevail.