Come to the duck side simply place the glow in the duck on the water and watch the automatic colour changing led bulbs light up and slowly cycle through colours the internal light turns on with contact with water and off when duck is removed it takes like a duck to water the battery lifetime of the glow in the duck is about 45 hours the equivalent to 180 fifteen minute baths all ducks contain x3 lr44 ag13 button cell batteries and colour changing leds batteries replaceable