TRUESHOP Rainbow Colors Changing LED Lighting Cup | Magic Color Cup with LED Light Multi Purpose Use | Liquid Activated Lighting Transparent Acrylic Inductive Mug Cup for Cold Drinks This cup is environmental protection transparent shine cup when pour into liquid (water, beverage, beer, etc), it will light up and flash immediately, very magical, suitable for celebrate, party, bars, gifts and so on. Water induction cup, if no water in the cup, it will not light up. Suitable for: bar, discos, restaurants, leisure, party, friends gifts, etc. Power: button cell X 2 (included). To Replace Batteries: Unscrew the battery compartment door located on the bottom of the base, place new batteries in the battery compartment and screw on the battery door. Bright colorful and fun beverage glass with assorted colors flashing in the bottom. Attract the attention of everyone at the party with this fun, bright, and colorful flashing beer mug.