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! Don't waste your money on the cheapest set you can find on eBay unless you want a cheap blade that will not perform! This sale is for 3 replacement XHT blades. EXMARK 103-8251 103-8251-S 103-9614 103-9614-S 109-6460 109-6460-S (3) needed for 46" Cuts. Center Hole: 15/16" Width: 3" Thickness: .197" Length: 16-17/64" Medium lift Notched blades 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.