I copied this from one of my replies regarding this same light in another thread titled something like "My new EDC from Target":
http://candlepowerforums.com/vb/showthread.php?t=92186
Here's a link to Quickbeam's review of the Nuwai version:
http://www.flashlightreviews.com/reviews/nuwai_tm-311h_2aaa.htm
I picked up a couple of the Rock Rivers in silver color a couple hours ago for my step son and son in law who never seem to have a flashlight handy. I got silver so they could find them more easily than the black (they have young children). I already have four of original Nuwai versions.
The Nuwai versions are NOT regulated, so it will be ineresting to see if these River Rock really are regulated, or just repackaged Nuwai. Someone did some runtime graphs a while back, but I'm not sure where to locate it.
The tail cap on the River Rock is slightly different than my Nuwais which were purchased last spring from Amondotech.com for $14.95 each. The River Rock tail cap is just a little longer and the black button is smaller. This results in the River Rock light being a little longer by the same amount. I don't have a preference for either version of the tail switch. All of the other physical/mechanical characteristics of the River Rock appear to be identical to the Nuwai.
The beam patterns appear to be nearly identical. The tint on both of the River Rocks are nearly identical to each other and both are more bluish than all four of my Nuwai, but not blue enough to be annoying to me.
The hot spot of the Nuwai appears a little larger and maybe a little bit brighter, but relative brightness is a little difficult for me to determine with my naked eye because of the difference in tint. I don't have a light meter.
In the above beam shot comparisons, the Nuwai appears to be dimmer than the Rock River. With my Rock River and Nuwai 2AAA lights, that does not appear to be the case.
I also EDC my Nuwai versions and also turned the clip around for bezel down carry. I've been very pleased with them so far.
ALSO CHECK OUT THE RIVER ROCK 2AAA .5W TWO POWER LEVEL HEADLAMP! it was located in my Target next to the Rock River 2AAA pen light! I also picked up one of these also and am please with it so far. The beam characteristics are similar to the 2xAAA pen lights described above, but it has a slightly larger and noticibly brighter hot spot and more throw and fewer artifacts in the beam. The head lamp reflector is about twice the diameter and a little deeper. The head strap has the top strap as well as the regular strap. The switch is reverse clicky with momentary off, but no momentary on. First click is low, second click is high and third click is off. This is a very nice feature. The low is lower than the pen light and the high is brighter than the pen light. Great throw for such a small light. The battery compartment has an odd cap mechanism and putting the cap back on in the light was challenging, replacing it in the dark might prove near impossible. The switch gives good tactile feeback and is loud, as is the angle adjustment, which is hinged on the bottom and adjusts from straight ahead to past 90 degrees down. I may post a separate review for the headlamp.
I didn't mean to hijack the thread, but if you like the pen light, you just may like the headlamp. It may even be a decent bike helmet light.