This glass contains a clever gimmick enabling you to show the glass full or empty at any time. You can fill it with milk or a coloured beverage such as orange juice, red wine, coke etc. An example: You show the glass full, drink it all up, place the glass for a second inside your jacket, behind your back or under a hat and when you bring it in view again it is filled up again. Can be repeated as many times as you like. Plastic glass.