The Following.Hex Flange Nuts Plain Black Size: 1/4-28Quantity: 25Flange Nut Specs:Diameter: 1/4"Thread: 28 TPI (Fine Thread)Wrench Size: 7/16"Flange Diameter: .574 min ~ .594 maxNut Thickness: .222 min ~ .236Grade: 8Finish: Plain Black Steel with light oilMaterial: Steel