Used in an aquarium. We bought six on January 30, 2018. The last one was delivered today, September 10th, 2020. The light is designed for 12 hours a day. The packaging states that the average lamp life is 5000 hours. At 12 hours a day, they should each last 417 days. The six bulbs I bought should last almost seven years. Instead, the five lightbulbs lasted 954 days, or about 191 days each. They lasted less than half the time stated.