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 2 replacement XHT blades. Replaces the following OEM part numbers: This is the Predator commercial mulcher blades! JOHN DEERE: GX22151 UC21583 2 BLADES NEEDED ON 42" CUT MACHINES WITH 7 Star lobe center hole! Fits the following models E100 E110 E120 E130 E140 Center Hole: 7 lobe" Width: 2-1/2" Thickness: .197" Length: 21-3/8" 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.