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. HUSQVARNA 539113425 522037401 (3) Needed for Some 48" CUT DECKS Center Hole: 5 point Width: 2-1/2" Thickness: .204" Length: 16-1/4" **DISCLAIMER- WE LIST BLADE PART NUMBERS, MODEL NUMBERS AND DIMENSIONS FOR REFERENCES BUT IT IS UP TO YOU TO BUY THE RIGHT BLADES. If you order them and they don't fit it is not our fault! We always accept returns but the shipping to and from will be your responsibility unless we make the error.