The Fenix TK72R is the most powerful flashlight I've ever tested, and it gives off way more light than anyone could ever need. Before I get into the specifics of this flashlight, however, I must share the manufacturer's warning with you, because it's the best.

I'm not going to lie, I was sold on this flashlight after reading the warning. Not only that, but the warning sheet that comes with the flashlight is even more specific and... awesomer?

Of course, I only had one question after reading the warning: will it really start paper on fire? That's the first thing I tried. No luck. I'm sure it would work under the right conditions, but I didn't try too hard. I simply held the flashlight against a piece of paper until the flashlight was too hot to hold.

What's surprising about this flashlight is how fast it gets hot; at the full 9000-lumen brightness, you can feel the head getting hot quite quickly. Uncomfortably hot. It won't stay at full brightness for very long, however. The graph below shows how the brightness drops off fairly quickly, leveling off at 2500 lumens after only a few minutes.

Size and Shape
This flashlight is a tank.

I think the "TK" in the model number probably has something to do with "tactical", but in this case, I'll assume it means tank. This definitely isn't the type of flashlight that you slip into your pocket. It's too big and too heavy. The good news is that it comes with a nice heavy-duty carrying case, and it slips in and out of the case quite easily. The case also has a velcro strap to keep the flashlight from falling out. Good stuff.
Controls
I had to read over the control instructions a couple of times to get it. There are tons of settings, and you can read about them if you want to, but it's not necessary. I gave the flashlight to my 7-year-old daughter and told her to make it bright. She figured it out in about 3 seconds. The short version is that you can hold down the plus and minus buttons to increase or decrease the brightness in 1,000-lumen increments or quickly touch them for 100-lumen increments.
Power and display
The TK72R comes with a gigantic 7,000 mAh rechargeable lithium-ion battery.