These Submersible LED Lights feature an On/Off Switch and are ready to use out of the box.They use 2 x CR2032 Batteries which are included and are already installed. These batteries are replaceable! These reusable, submersible LED lights,are waterproof and wireless and are thus perfect for lighting up vases, bowls, or any water filled containers. They can turn a boring bowl into a beautiful and exciting centerpiece. These submersible lights are often used for event design.They make great party favors as well.The submersible light can be turned on or off by twisting the base of the unit. The battery life of the lighting unit is about 72 hours. Our LED lights are fun, safe and perfect when you need an alternative for candles in order to meet fire codes or to avoid the dangers of an open flame.