XHT (Xtreme Hardness & Toughness) blades feature a unique steel that incorporates boron, carbon, manganese, and other materials that ensure its strength. The blades are heat treated with the patented and independently tested Marbain heat-treating process. This process makes the blades 25% - 40% harder than standard lawnmower blades, making them the longest-lasting, safest, and most impact resistant lawnmower blades on the market.    Center Hole: .531"    Length: 17.350"    Replaces: Ariens / Gravely: 3971900    Thickness: .187"    Width: 2.250"
