XHT -BOB CAT NON-NOTCHED 112111-01, Center Hole: 5/8″, Replaces: 112111-01, Type: High Lift, Web Notes: 40% harder than standard lawnmower blades, making them the longest-lasting, safest, and most impact, Web Notes: resistant lawnmower blades on the market., Web Notes: manganese, and other materials that ensure its strength. The blades are heat treated with the, Web Notes: patented and independently tested Marbain heat-treating process. This process makes the blades 25% -, Web Notes: XHT (Xtreme Hardness & Toughness) blades feature a unique steel that incorporates boron, carbon,