These deep drop lights are Water Activated, they turn on when in contact with water. Boasting a 250 hour battery life, these lights can be used for mulitiple drops unlike the single use glow sticks, and they are also brighter. With a maximum depth of 3000 feet, these lights are perfect for swordfish, grouper, tilefish, halibut, and many other deep water species. Batteries are pre-installed in the lights and non-replaceable.