Oregon Fusion 3-N-1 Mulcher Blade For 54-Inch John Deere Lawn Mowers 491-470 Replaces OEM No. M143520, and M145516 Order 3 for a 54-Inch Cut Blade Length (Measured Diagonally): 18-29/32in. Center Hole Diameter: 51/64in. Width: 2.50in. And Thickness: .250in.