Outer & Inner Flange Lock Blade Bolt Key for Rockwell 4-1/2" Compact Saw RK3441K Worx WX429L Outer and inner flange nut for 4-1/2" Rockwell / Worx Compact Circular Saw Kit included :Outer Flange, Inner Flange, Bolt Screw and Hex Key (1ea) For Rockwell / Worx 4-1/2"compact saw RK3441K/WX429L IT NOT for Rockwell 3-3/8" Versacut saw This is aftermarket kit , but fully compatible