HIPA (Pack of 2) Air Filter for STIHL STIHL HT101 HT130 HT131 FS90 FS100 FS110 FS130 String Trimmer # 4180-120-1800 Replacement manufacturer part number: 4180-120-1800 Fitment models: STIHL FS90 FS100 FS110 FS130 HT101 HT130 HT131 trimmer