Both. I got my TK20 on clearance, and when I noted that it didn't seem as bright as I expected, someone on candlepowerforums told me that what I got was the discontinued older version, and the newer ones would be brighter. I don't know that for a fact - it's just second hand info. In general, though, LED technology is always increasing, and many flashlight companies will bump up to newer LED's in their lights as they become available - often without clearly telling you the difference, so it's really confusing.

The TK20 is plenty bright for normal flashlight duties, and if you run it on low it has decent runtimes. It's only a two-mode brightness though. It's a bit bulkier than some other 2xAA flashlights, but also has the rubberized grip, which is great in cold weather.

The other Fenix 2xAA lights are higher end - the TK20 is more of a simple, stripped down base model.