Includes (1) 91-392 Mower Blade. Genuine OEM False Replacement Part . Oregon 100 Series Blades offers Ultra X-tended Cutting Length , which means that each blade delivers its maximum mulching capability per rotation. Add that with our double bevel technology and the overall blade noise is reduced by up to 1.5 decibels. The 191-392 blade is made from Boron Steel that allows for the perfect balance between durability and ductility.. Center hole: 11/16″. Reduces overall blade noise by up to 1.5 decibels. Compatible with the Following: