this is a 25.4 millimeter by 1inch brush. It is a Stihl made Steel Knife Blade

Genuine STIHL OEM Factory Part

Before installation, make sure that your brushcutter supports the use of metal blades with a 25.4 mm mounting hole.

Compatible with the following models: FS90, FS91, FS91R, FS94, FS111, FS111R, FS111RX, FS131, FS131R, FS240, FS240R, FS250, FS251, FS251R, FS311, FS361, FS361C-EM, FS410, FS461C-EM, FS460, FS490, FS510, FS560, FS561C-EM, FSA135, FSA135R, FSA200, FSA200R, FSB-KM, KM56RC-E, KM91R, KM94R, KM111R, KM131R, FS-KM, KMA80R, KMA120R, KMA135R