A specially designed aluminum 2 1/2 inch side pour sand casting flask is recommended for use with fine-grain sands such as Red Clay and Delft. The flasks are designed to "key" together for proper alignment. The flask measures about 2 1/2 inches in outside diameter and 2 1/8 inches in inside diameter, with a 2-inch width. The pouring hole is approximately 1 inch square. One 2-part aluminum sand casting flask with stand is made in the USA with solid aluminum for long-lasting use.