ST15855 air filter replaces Stihl trimmers air filter Stihl 4180-141-0300B. Fits Stihl FS111, FS91, FS131 Trimmers using Stihl air filter OEM# 4180 141 0300B, 41801410300B, 4180-141-0300-B, 41801410300-B. 19-15855. Refer to your manual to match by OEM#