True Spike flat seat steel wheel adapter washers to True Spike Acorn lug nut. This washer will allow for a proper seating surface when using any True Spike Acorn lug nut, which all have 60-degree seats, with your typical dually flat wheel surface. For wheels that have a flat face where you cannot use an acorn lug nut. Specifications: Color: BlackFinish: Zinc PlatedInside Diameter: 0.65 (21/32, 16.51mm)Material: Hardened SteelOutside Diameter: 1.35 (1-11/32, 34.29mm)Quantity: Sold in packs of 4 Seat: Cone/Tapered (60°) -TO- FlatShap