Sometimes when you prepare a roast or have made stock, you need to separate the stock from the fat that's come out of the meat. You can do this by refrigerating the stock and then skimming off the fat layer that rises and sets at the top of the stock. Don't have enough time to do all that? No problem - use this separating jug instead.Allow the stock to settle for about 5 minutes and the fat or oil will float to the top. When you pour from the jug, the stock is taken from the bottom of the jug because of the positioning of the spout. The fat or oil is left in the jug. Just stop pouring when you see that most of the stock has been poured off. Ingenious.The jug - or this one anyway - comes with a strainer. I don't think I have ever bothered to use mine and I really wouldn't know where to find it now.