JoshthePollock

I have looked through the forum a good bit, and the best possible help for looking for LED's was this post:
Reading through that post helped explain to me a lot, and I have a cpl who is also helping me with my idea of installing LED's in my footwells and doors, but I can't find a proper LED for the life of me. Most of the links from that post are outdated.
I've looked on eBay, and according to it, some lights are "not compatible." But the only time I've ever known electricity to be incompatible is an AC/DC current with no converter. Anyone care to explain this to me?