QualityParts From Oregon That you can depend on. Center hole: 1/2": Requires 3 blades for 54" and 55" cut; X-Tended Cutting Lengthâ„¢ optimizes the cutting efficiency with each revolution.; Superior mulching for bagging and discharge efficiency; Enhanced hardening to keep the blade sharper and more durable; Replaces major brand: Bush Hog; Oregon Equipment Parts 92-149 Blade Bush Hog 50056494