This submersible cool white LED light is super bright and really easy to use. You will get a set of 12 and they feature an on off button for easy use. Press the button once for a steady light, twice for fast blinking, three times for a slow twinkle, and a forth time to turn it off. We tested one and it continued to work on the slow twinkle setting for 3 weeks. We left it on for the entire time. Your results may vary but they last a long time on the batteries they come with. These small, yet mighty lights are 1" tall and 1.25" in diameter. Use them in vases, bowls, and other centerpiece displays. The batteries are non-replaceable but do use long lasting 2scr2032 lithium batteries.