Sunbelt B1JD6015 21-1/2-in. XHT Lawn Mower Blade for 42-in. Decks is designed for mower decks with a 42-inch cut, including popular brands like Scotts, Sabre, and John Deere L and 100 series. This blade measures 21-1/2 inches in length, 2-1/2 inches in width, and has a thickness of .156 inches. It features a center hole diameter of 11/16 inches and outer holes that are 13/32 inches in diameter, spaced 3-3/4 inches apart from center to center. The medium lift blade is sold as a single unit. Sunbelt's XHT (Xtreme Hardness & Toughness) blades utilize a patented Marbain® heat-treated steel, which has been independently tested to provide enhanced hardness and superior resistance to bending and impact damage. This technology allows the cutting edge to stay sharper for a longer period, making XHT blades approximately 25% to 40% harder than standard lawnmower blades. These blades the tightest tolerances when d to equipment blades across all makes. This blade is equivalent to John Deere GX20249, GX20433, GX20819, GY20567; Oregon 91-139; Rotary 10635; and Stens 330-615. Model Number: B1JD6015