The 3 teeth eater blade fits for stihl, echo 1" (25.4 mm) or 20 mm arbor.
Lawnmower Blade Adapter Replacement parts as following:Thrust washer:4130-713-1600;Rider plate: 4126-713-3100;Collar nut:4126-642-7600.
FITS FOR FS160, FS180, FS220, FS280, FS300, FS350, FS360 C-E, FS920, FS410 C-E, FS450, FS460 C-EM, FS480, FS490 C-EM.
These brush blades will cut anything from brush, weeds, saplings, and twigs.
NOTE: This replacement kit is an aftermarket product produced.