XHT BLADES Extreme Hardness Toughness MADE IN THE USA! Don't be fooled by other cheap imported blades you see on eBay! Buy from home! The XHT blades are made with MARBAIN which is what makes them THE BEST BLADE ON THE MARKET! Increased hardness (between 48-52 on the Rockwell Hardness Scale), without brittleness Greater yield strength—the strongest mower blades on the market Better impact toughness (ANSI-S483 compliant) Increased resistance to bending Higher wear resistance Reduced weight Faster start/stop Less wear on PTO clutch break Lower fuel consumption Last longer and need to be sharpened less frequently Our patented MARBAIN material is a durable, cost-effective alternative to abrasion resistant steel and other manufacturing materials This sale is for 3 replacement HEAVY DUTY XHT blades. Replaces the following OEM part numbers: JOHN DEERE M145516 M143520 NON MULCHERS Center Hole: 51/64" Width: 2-3/4" Thickness: .187" Length: 19"