REPLACEMENT XHT BLADES Extreme Hardness Toughness Replacement XHT Lawnmower blade. XHT(Xtreme Hardness & Toughness) blades are 25-40% harder than standard lawnmower blades. Benefits of the HXT blade are sharper and longer lasting cutting edges. More resistance to bending. Tighter tolerances in the aftermarket vs. OEM. XHT blades also offer greater impact toughness. By the way they are made in the USA! Hands down the ABSOLUTE best aftermarket replacement blade on the market! This sale is for 3 replacement HEAVY DUTY XHT blades. Replaces the following OEM part numbers: EXMARK 1-323515 1-403059 103-6583 BAD BOY 038-4820-00 Center Hole: 5/8" Outside hole: 11/32" Center to Center on outside holes: 1-5/8" Width: 2-1/2" Thickness: .250" Length: 16-1/4" Please make sure you are ordering the correct blades. We list model numbers, part number and the exact dimensions so you know exactly what you are getting. Just because the model number is not listed does not mean it doesn't fit but are because it is listed to mean it does. There are serial number breaks and other factors that sometimes change needed blades.