Pros: I placed this driver in my Ultrafire C3 as an upgrade, and it really is an upgrade. The C3 has a greater light output and the five modes are really useful.
The driver contains of two parts, a booster to boost the voltage to approx 3.2 volt (Vf) and a second pcb on top for the five modes.
The print is using a PIC controller of Microchip for the 5 modes so there is a possibility to write your own programs and put them into the driver. (if you have the hardware, software and knowledge for it)
The efficiency of the print is about 65-75% with a fresh charged NiMh cell and about 80% when the battery is almost empty (Vbat<1.0 volt)

Cons: With NiMh cells I can't get a 500 mA current. The output is not constant current, the driver is boosting the voltage to it's maximum, there is no resistor for feedback, the led is coming between the coil and the ground.
On low you can hear pwm noise.
This driver can't handle two AA batteries.

Other Thoughts: This driver has five modes, a high (100%), medium(I guess 50%) and a low (Guessing 10%). The strobe is quite fast, it should be something like 7 flashes each second. The last mode is a sos mode, and it is a real sos mode (three short, three long, three short, 1 second nothing, three short, three long, three short 1 second nothing ect)
On a fresh charged NiMh cell (Powerex 2700 mAh or P 2700 mAh) the pcb is using 1.2 amperes from the battery. On medium this is 800 mA and when the output is set to low the corercnt that leaves the battery is 500 mA.
I did some measurements with the driver:
Input Voltage: 0.9 1.2 1.5 2.3
output current: 60 mA 270 mA 550 mAh 2800 mAh
efficiency: 80% 65% 70%
Even at 0.8 volt the output current was 50 mA. A lower voltage I couldn't test, my power supply can't get to zero volt.

Bottomline: Nice driver for upgrading. Too bad it isn't a constant current driver. Five modes are really handy.
This driver a very nice for upgrading a single AA Ultrafire C3 flashlight

Pros: This driver provides 5 decent modes and a good but possibly confusing mode memory. I got 3 that looked as pictured and did not have multiple groups as described in the review below. Modes: hi/med/lo/super fast strobe/true SOS. The SOS was not super slow, either, better than what seems to come in most lights. I put this in a Tank007 single mode with a Q2 and increased the brightness to about 110 lumens (1200mA). Medium was about 70 and low about 30. No PWM flicker.

Cons: Brightness declines throughout the voltage range on high, but remains fairly constant on the lower modes that are fairly inefficient. I found medium to be about 66% and low about 33% on power consumption. The amount of light from a CREE Q2 is disappointing at less than max for the power consumption, but a good NiMH will run it for hours, so no big deal. The board is a bit big to put in a typical AA pill. I had to grind down the smaller 2nd deck to get it in, the lower remaining out. Still worked okay. When grinding, the black emitter lead broke off (barely soldered on) but was easily put back.

Other Thoughts: The mode memory holds the last mode when you turn off for more than a second. To change modes, turn on and depress reverse clicky again in less than a second. If in a mode over a second, it takes two presses to start changing modes. Seems a little confusing if you don't keep the rules in mind. I tried 3 volts for a split second and got 2.7 amps draw, so it isn't for 2 AA or lithium.

Bottomline: Makes a dull single mode light brighter and more useful. The mode memory works well and the modes are well implemented.

Pros: Total 16 Brightness modes in 3 groups:
- 1) Lo-Mid-Hi
- 2) Lo-Mid-Hi-Fast strobe-Warning strobe-3Hz Slow strob-1Hz Slow strobe-10-sec Beacon
- 3) Lo-Mid-Hi-Fast strobe-SOS
Has a memory/
Blink after 2 sec -Remembers a mode.
5 seconds in a low mode - blink - change a group.

Cons: Two of three drivers do not work :(

Other Thoughts: The working driver has put in Jetbeam C-LE2 instead of burned down. It was necessary to grind a file slightly to reduce diameter.

Bottomline: The good driver

Pros: It has simple installation - nothing else needs to be set. Boosts voltage from just one AA or AAA cell. Five interesting modes of operation for the attached light emitting diode.

Cons: Pre-soldered wires are very weak. Some of the modes stay active after I've power cycled the device (it may be the particular switch I've used). This can be annoying if the one-hundred percent mode is desired quickly.

Other Thoughts: Might be worth looking at other units if you need to work with higher current. This unit was used with the ultraviolet module available as sku4334.

Bottomline: Good for simple, light applications where you are limited to a single cell and planning to use more than a one-watt light emitting diode.