Blade-Mower, Xht, 21", 2-1/2" 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.(3) blades for 61" cut    Center Hole: 5/8"    Length: 21"    Replaces: Bobcat: 112111-03 (Non-Notched Version)    Thickness: .197"    Width: 2-1/2" Bobcat Riding Mower XM SERIES
