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" Â· Disclaimer: We list model numbers and part numbers for references only. At times the same model may take different parts based on serial number breaks or manufacturers specifications. We list all the specifications on the part (size, width, length, thickness, etc.) and YOU must know what is needed on YOUR application. We canÂt possibly make it more known as to what you are receiving when you purchase.