Bosch USR7AC Spark Plug fits Stihl HT73, HT101, HT102 Brushcutters. Genuine Bosch Plug. OEM No. USR7AC. Suitable for the Following Applications:. HT73, HT101, HT102, HT103, FS83, FS83T, FS89, FS89R, FS90, FS90R, FS91, FS91R, FS100, FS100R, FS100RX, FS110, FS110R, FS110X, FS110RX, FS111, FS111R, FS111RX, KM90, KM90R, KM91R, KM100, KM100R, KM110R, KM111R, FC 90, FC 95, FC 91, FC96, FC 100, FC 111, HS81, HS86