This is a replacement notched disc blade for use in on your farm, garden or field. This notched blade measures 20" in diameter and is 4.5mm thick. The notched blade has a square double punched hole measuring 1-1/8" x 1-1/4". These notched blades are new and ready to be put to work. If you have any questions about whether this blade will work for your setup, please contact us to avoid costly return shipping fees. Someone on our staff will be more then happy to answer any questions or concerns you may have. Part Number: 20Nx4.5