John Deere GX21784 Standard Mower Blades for 48" Deck Mowers. John Deere lawn mower blades are manufactured with a combination of carbon and boron to provide hardness for a long life and sharp edge without breakage. John Deere conducts extensive testing to ensure wear and longevity on all products. Set includes three (3) blades. A genuine John Deere Original Equipment Manufacturer (OEM) part.