4.25 ounces. Appears solid; not hollow. Square nut on one end, I’d guess there is a stud on that end. 2 of the sides, on the large end, are flat. These are on opposing sides, 180 degrees apart. It resembles half of a rear end/final drive for a toy vehicle. But it’s extremely heavy and we’ll built if it is. Found around a bunch of square nails and old sandstone foundation stones. Thanks