Metal Brass Knuckles Paperweight Black Belt Buckle. Our Black Iron Fist Knuckle duster makes a perfect paperweight in the office or around the house. Screw in the buckle pin and transform this knuckle into a buckle. It features four finger holes with each carrying a rectangle design on the front. It is sports a glazed black finish with large finger holes measuring approximately 25.78mm in width and 26.74mm in length.