The Tank007 M20 flashlight (the model with the hex end) has five modes, a rotary switch, and no instructions. Here's how to switch modes: turn the head counterclockwise to turn off, and clockwise to turn on. Turning the light from on to off and then immediately on again switches to the next mode, in this order: medium, low, high, strobe, and flashing.
I'm posting this because I had to search the web for a while to get a clue. This may be completely obvious to everyone else, but I was stuck when I switched it to strobe mode and didn't know how I did it or how to switch back. Thankfully, someone posted the instructions for a similar light.