Wing nut Genuine Stihl Part OEM Part No. 4138 716 1200 Suitable for the Following Applications: HT70, HT75, HT100, HT101, FS40, FS40C, FS50, FS50C, HT73, FS38, FS45, FS45C, FS45L, FS46, FS46C, HT130, HT131