Oregon 518244 Universal 3-In-1 Gator Mulcher Blade, 21" 21 inch Oregon Universal blades # 518244 Blade length (measured diagonally): 21 inch Blade width 2.5 inch Blade comes with an adaptor kit. It fits most walk behind mowers (excluding Honda, Lawn- Boy and Toro). Contains adapters for 3/8", 1/2", 5/8", & 11/16" center holes, plus 3/8" & 5/8" center hole blade washers