Oregon Fusion Blade For 42-Inch John Deere 100 Series Lawn Mowers 491-139 Replaces OEM No. GX20249 and GX20819 Order 2 for a 42-Inch Cut Blade Length (Measured Diagonally): 21-3/8in. Center Hole Diameter: 11/16in., Outer Holes Diameter: 13/32in., Center-to-Center Distance of Outer Holes: 3-45/64in. Width: 2.50in. And Thickness: .164in.