XHT blades are made from the highest grade of steel for the best cutting and performance money can buy. With the best hardness, strength, and durability in the market, this range of blades is recommended for every mower in the market. They are stronger, harder, and last longer in any environment. 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!********This sale is for 3 replacement USA XHT blades. These are the real deal .313" thick blades! Replaces the following OEM part numbers: JOHN DEERE AM100538 M141785 M87622 3 NEEDED ON 60" MODELS Center Hole: 29/32" Width: 2-1/2" Thickness: .313" Length: 20-1/2"