Come and Check Our Branding Solutions.Water clock has no batteries, as long as the bottle is filled with water in the back of the clock, it can clearly display the time.A few weeks later, remember to change water.This water clock without the alarm function.It's easy to set, just press the button "MODE" and "SET" to set the clock, can be functioned as a learning clock as well. Pls check inventory and detailed info before placing your orders.