Okay, I have a couple of lights that each use 2 fluorescent lights. When I put these two new bulbs in the lamp together, they don't light up, they fight, but they don't light up fully. However, when I separated them and placed them in different fixtures along with other lamps, both worked. Big. I'm not sure how I feel about this. Edit: A few months later they are blinking. unreliable rubbish (actually I think they could be used) DO NOT BUY