I've been using Sylvania 3156 Longlife bulbs for over 10 years, 4 hours a day, 365 days a year. Not a single burned out lightbulb for the whole time. I bought them and they are (a) the same size, (b) plug and play, and (c) look a little brighter (to my unexperienced eye) than the Sylvania. Of course, after so many years in the light, the Sylvanias were a bit dirty, and that might be why they became less bright. I haven't had any polarity problems inserting them, even though they're diodes.