This product contains a built-in lithium battery, so there is no need to prepare your own batteries. It is ready to use once fully charged. Before using the product for the first time after receiving it, please charge it for 90 minutes. The product can be charged using a standard household USB charger. Please note that all mesh nebulizers are unable to atomize pure water or distilled water. When you receive the device, please test it with tap water or saline solution.