QualityParts From Oregon That you can depend on. Center hole: 13/16": Requires 1 blade for 21" cut; For walk-behind mowers; Superior mulching for bagging and discharge efficiency; Enhanced hardening to keep the blade sharper and more durable; Replaces major brands: Snapper, Cub Cadet, Craftsman, and MTD; Oregon Equipment Parts 98-007 Blade Mtd 942-0721 20-15/16I