Monitor RPM data for engines with the Graupner RPM Optic Sensor. Specifically designed for compatibility with the General Engine Module (P/N 33610) and the General Air Module (P/N 33611), all functions of this RPM Sensor can be set and programmed using a HoTT radio or SMART-BOX. Real-time RPM data information can be displayed on the radio/telemetry screen or via voice announcement.