21" High Lift mower blade replaces John Deere OEM# M163983. Width: 2-3/4", Thickness: 0.197", Center Hole: 29/32". Fits 60" high capacity decks Models X710, X730, X 734, X738, X739, X750, X754 and X758. Order 3 blades for 60" deck. Similar to Oregon# 91-078, 91078, A&I# B1JD1054 and M96730. Refer to your owner's manual to match by OEM part #. 

XHT (Xtreme Hardness & Toughness) blades feature a unique steel that incorporates boron, carbon, manganese, and other materials that ensure its strength. All blades are heat treated with a process makes the blades 25% - 40% harder than standard lawnmower blades.