I've used them in the past; they weren't the best. My main complaint is that they seem to burn out and get weaker quicker than most other MV bulbs on the market. You're supposed to change them out every 5-6 months, but I had to replace them sooner than that due to the issues I stated in the first sentence. I much prefer the Zoo Med Powersun, while it may be more expensive you do get what you pay for. Here is a survey about what the TFO member think the best MV bulbs on the market.