I ordered the last 4 they had at that time, because I had to use the last replacement bulb I had at home, when 1 of the bulbs blew the night before. While they had 4 in stock at very reasonable prices and they were delivered in great packaging. Until another bulb blows, I'm not going to mess about trying them out, to check if they work or not. I have to assume they will and these bulbs only last about a year, so with 2 lights being used for my birds, 1 bulb should get changed within the next few months. Customer service was great when i contacted them to see if they had any more or getting more in. I don't like giving 5 stars for something I haven't even tried yet, but I gave them, because everything so far, is 5 star :)