During the last week, I had to replace a 500w GE pool light bulb that had been operational for over 12 years. I found these Feit bulbs at a local store. The first 500w bulb I installed would stay on for about 10 minutes, then it would turn off on it's own. It would come back on about ten minutes later and turn off again after a period of time. I had an electrician check the wiring and the fixture and he found no problems. His best guess was that the 500w bulb was overheating in the Hayward enclosure and shutting down.So, I tried the Feit 300w bulb as a alternative. The store exchanged the bulbs with no questions asked. When I installed the 300w bulb, it came on with a flash and shut off. I tested the fixture and found no voltage problems or surges. The GFI breaker did not trip. I exchanged the first bulb and got another replacement at the store. After installation, it did the same thing. Neither 300w bulb would light after the initial flash.I went to another pool store and bought a 300W GE bulb, which worked just fine after installation. No problems at all. I have to think that the store got a bad batch of these FEIT bulbs and I was the unfortunate consumer.I would stay away from this chinese manufactured bulb. The GE pool light bulbs are far superior.