User manual: 1.Inductive light. 2.Light is on when the cup is filled with liquid(water、drink、alcohol etc). 3.Fliching thythm is changable automaticly. 4.Light is off when no liquid's filled in. 5.Cleaning with water. Battery-changing instruction: 1.Two batteries are at the bottom. 2.Open the lid with screwdriver、put two batteries in、close the lid. Dimensions: 3.35 in x 2.76 in x 3.35 in (8.5 cm x 7.0 cm x 8.5 cm) Weight: 3.53 oz (100 g)