Echo 99944200418 Blade Conversion Kit 20mm Arbor (No Blade)Echo 99944200418 Blade Conversion Kit 20mm Arbor (No Blade) Echo blade conversion kit (99944200418) offers more versatility with your Echo SRM trimmer. From trimming the lawn to cutting through dense weeds and underbrush, our blade conversion kits deliver convenience and unit flexibility. With standard 20mm size arbors the blade conversion kits fit a variety of Echo SRM models. Kits come with or without a brush blade so you can customize your trimmer