It's a 5V LED rather than the more common 12V . This was exactly what I needed as I wanted to power them from USB.
I used them with the Gold Effect Illuminated Arcade Buttons on this site. They fit the LED mounting fine (just slot in) and do what they're meant to do - light up.
I can't vouch for whether they will last a long time as I only just got them, but they seem fine to me.