These re-usable, waterproof, battery operated submersible LED lights are perfect for lighting up water-filled flower vases and glass bowls. They also work great with glass marbles and gems for that eye-catching lighted centerpiece display. Each little light is about 1.25 inches in diameter by about 0.75 inches high. They can be turned on or off by twisting the base of the unit. Each light uses two CR-2032 batteries (included and replaceable). The batteries typically last 48 hours or more before needing to be replaced.