Very cool unique party cup. It has L.E.D.'s that chase each other in the bottom of the cup and due to the design with the crystal it makes the glass illuminate with  4 different colors every where. It's extra sturdy, food grade acrylic with 5 flashing and motion sensitive red, yellow, green and blue LED lights inside. Screw off base for easy washing. Batteries are included and replaceable (Watch Battery). Water resistant.