This Emperor Aquatics 40W (33.5") GT5 UV Sterilizer replacement lamp is a genuine Emperor lamp sold to us by Emperor (there are many companies selling cheap knockoffs). It will work with all Emperor Aquatics 40W UV Sterilizers.
UV lamps should be replaced every year. When replacing the lamp it's also a good idea to replace the o-rings. The Emperor Aquatics Smart Lite UV Sterilizer Service Kit has all six replacement o-rings. By replacing the o-rings you will greatly lessen the likelihood of leaking that may destroy the bulb and ballast.
NOTE: If your UV lamp is not lighting up and you've only been running the lamp for a two years or less, there is a very good chance the lamp has not burned out. Emperor lamps typically stay lit for years, but need to be replaced yearly because they lose intensity. The problem might be the Power Supply.