I am using GE daylight and they say 13 year guarantee on the box. They are at least 2 times as much money as all the imported ones. I have used Walmart and similar and they never last. I tried OSRAM made in Germany and they sucked for brightness. All my lights are not enclosed. They are all open air fixtures with lamp shades and my ceiling fans all have 4 candelabra style. The longest I have gotten any to last is 3 years.