Got one. Lives in my shell jacket. Excellent build. Meant to be about 15 lumens IIRC so not far off a surefire KL3 (19 lumens). There's no electronic drive circuit so the intensity will just fade away over time. I've no idea how long it lasts in the real world as I've only used it for about 45 mins so far. Shop around and you can get them MUCH cheaper than when they were first introduced in the UK for £50+.
Cheers,
Cheers,