QualityParts From Oregon That you can depend on. Center hole: 1/2": Requires 4, 91-363 blades and 3, 91-364 blades per deck; Offers left-hand cut; Enhanced hardening to keep the blade sharper and more durable; Made to exact OEM specifications; Replaces major brand: Jacobsen; Oregon Equipment Parts 91-363 Blade Jacobsen 23In Lhc[431]