Castro CoolerBobs lights for Pools, Parties, and Coolers, Each Coolerbob uses 2 watch batteries that can be easily replaced. The battery life ranges from 24hrs continuous to 36hrs using the strobe mode. We have added a push button on/off switch for ease of use. Coolerbobs are the best add on available for any cooler. With your choice in color, and light setting, you can now customize YOUR cooler. Remember to think of your fisherman, hunter, hiker, camper, tail-gater, and all around outdoorsman.