Air Filter replaces Stihl 4140-124-2800. Fits String Trimmers FS 38, FS 45, FS 46, FS 55 & KM 55 Edger FC 55 Hedge Trimmer HL 45, HS 45. Used on Stihl Models FC55, FS38, FS45, FS45 C, FS45 L, FS46, FS46 C, FS55, FS55 C, FS55 R, FS55 RC, FS55 T, HL45, HS45, KM55,KM55 C, KM55 R, KM44 RC.