QualityParts From Oregon That you can depend on. Center hole: 13/16: Requires 3 blades for 54" cut; High performance blade; Superior mulching for bagging and discharge efficiency; Enhanced hardening to keep the blade sharper and more durable; Made to exact OEM specifications; Replaces major brands: John Deere and Scotts Oregon Equipment Parts 91-404 Blade John Deere M135590