Apart from just impressing your friends, these are largely useful for people like me who explore underground and have a real need to light up large holes, hence these are referred to as "stope blasters".
These are often called "soda can lights" since that is their general size and shape.
This is more or less out of place, but here are some links to a place with good prices on 18650 batteries.
Moonlight (0.5 lumens/98 days) Low (46 lumens / 123 hrs), Medium (470 lumens / 15 hrs), High (2060 lumens / 190 minutes), Turbo (3660 lumens /120 minutes), Strobe (3660 lumens/234 minutes),Normally you get the L-M-H sequence by pushing the side button. A long push when the light is off gets you moonlight. A double click gets you turbo. These ratings may be a little less bright for the neutral white version.
There is also a "big brother", the TN36 which costs twice as much (about $200), and puts out twice as much light (7000+ lumens). It uses three CREE XHP70 LED emitters. It seems to be exactly the same size. I read reports that a fair number of people have received defective lights that will not switch into turbo mode. For this reason, as well as the sheer expense, and the idea that 3600 lumens is plenty, I am avoiding this light.
If you read TN30 reviews on Amazon, you may (or should) quickly realize that as those imbeciles so often do, they have mixed the TN30 and TN36 reviews, making the mix all but useless.
One nice feature of the Supfire is a 1/4-20 tripod bolt hole.
This light uses 4 18650 batteries in a parallel configuration. It uses three cool-white Cree XM-L2 LED emitters. The claim is that it will crank somewhere around 3000 lumens.
The price from Mountain Electronics is amazing at $42.50, even direct sellers in China are asking $56 or so. For an extra $15 you can get a firmware mod that provides a moonlight mode, but may have to wait a month or so for delivery.
Tom's Light Info / email@example.com