QualityParts From Oregon That you can depend on. Center hole: 13/16": Requires 2 blades for 42" cut; Superior mulching for bagging and discharge efficiency; Enhanced hardening to keep the blade sharper and more durable; Replaces major brands: Simplicity, Snapper, Allis Chalmers, and Massey Ferguson; ; Oregon Equipment Parts 91-605 Blade Snapper 1737816Bmyp 21