This listing is for (1). 7 Blade Set Complete Replacement Blade Set for a Jacobsen HR511 Lawnmower. Part # 91-363 4 Blades 23″ Length 1/2″ Center Hole 7/16″ Outer Hole 2 7/8″ Center to Center 2 1/2″ Width 1/4″ Thickness. Part # 91-364 3 Blades 23″ Length 1/2″ Center Hole 7/16″ Outer Hole 2 7/8″ Center to Center 2 1/2″ Width 1/4″ Thickness. The item “Jacobsen HR511 Lawnmower Blade Set Oregon 91-363 91-364 7 Mower Blade Set” is in sale since Friday, November 18, 2016. This item is in the category “Home & Garden\Yard, Garden & Outdoor Living\Lawn Mowers\Lawn Mower Parts & Accessories”. The seller is “theshelbymall” and is located in Shelby, Ohio. This item can be shipped worldwide.