Our Oregon 100 Series lawn mower blade is made from Boron steel, which allows for the perfect balance of durability and ductility. with the Ultra X-tended Cutting Length, the has improved cutting efficiency per rotation. The double bevel technology helps reduce overall blade noise by up to 1.5 decibels. 21.25 in. replacement lawn mower blade Fits Murray & Scotts 42 in. Cut Riders 3 N 1 Blade (Mulches, Bags & Discharges) Requires 2 Per Set