Dear Crystal Vander Zanden,

I am not shure about this, but I have a feeling that the original lamp for which this lamp housing and supply were designed was the HBO100, and that someone decided to put the newer, improved lamp HBO103 in the housing. From the specifications, it is to my opinion safe to replace these two. Life expectancy of the HBO100 will be shorter, but always better than a dead bulb. When in doubt, ask the representative of the microscope manufacturer about what to do. Exploding high pressure lamps are nothing to joke about. Kind regards, Harrie Verhoeven

I agree with Harrie. It sounds like it should work but a microscope rep would be the one to ask. I never burn an HBO bulb for much beyond 200 h and my microscope rep told me always turn the bulb on for at least 2 h since each time the bulb is lit it is 2 h of bulb life even if it's only on for 30 min. Thus, if you really don't know any details of how much time the replacement bulb has been used for, don't take a chance. The rep also told me when these high energy mercury bulbs blow it's like a bomb and although the housing will remain intact for safety everything inside is destroyed. At the time he told me the replacement cost would have been $5000 and that was 35 years ago. So be safe and sure before you simply replace one bulb for another.