Please note that this review is based on a test sample of the Quark X AA². The Quark X AA², is basically a two cell version of the earlier X AA². It's made of aluminum and coated in black Type 3 anodizing. The head has a pretty simple design with a smooth bezel. Behind this is an AR-coated sapphire lens which allows better light transmission as compared to regular glass. A lightly textured reflectors focuses light from the LED which sits slightly off-center at the bottom of the reflector cup. The coating on the reflector is nicely polished and consistent with no noticeable flaws. The exterior of the head is mostly covered in diamond-textured knurling which provides ample grip which is good since the light is twist-activated. Viewed from the rear you can see the PCB with electrical contacts for the battery.

The battery tube continues its simple, cylindrical design. It's almost totally covered in knurling on the exterior, with a slightly raised section towards the rear end. There is also a small lanyard hole at the tail end for lanyard attachments. The protruding switch cap menas the light isn't able to tail stand, but at least having a forward push button switch allows for momentary activation. Threads between the head and tail cap mate well and smoothly, no cross-threading or squeaking was experienced during testing. A well-lubricated rubber o-ring sits just behind the threads which provides a moisture seal. On the inside, the battery tube is cleanly finished and has a spring contact at the bottom which prevents the battery from rattling when the head is loosened while switched off.

If you're unfamiliar with any of the terms used in this review, click here for explanations on common flashlight related vocabulary.

Operating your Quark Tactical is simple. Insert the battery with the positive side (+) towards the head. Make sure the head and tailcap are tightened, then depress the tailcap button fully so that it "clicks" and the light turns on. You can also press the tailcap lightly (you don't have to "click" it on) to activate the light momentarily. This is known as the momentary-on feature.

The Quark Tactical can memorize any two modes of output, from its eight total modes, to be instantly available. These two memorized modes are accessed by either tightening or loosening the head (for example, tight can be Max, and loose can be Low).

Programming Modes:
To have your Quark Tactical memorize a different mode, turn it on and loosen the head by a half-turn. Then, tighten the head at least four times rapidly (twisting it tight, then loose, then tight, etc., four times). After the fourth time, leave the head tight or loose depending which position you want to program.

After three seconds, the light will flash, signaling it is ready to be programmed. Cycle through the eight available modes by clicking the tailcap off and on. The mode sequence is as follows:
Moonlight » Low » Medium » High » Max » SOS » Strobe » Beacon

Once you find your desired mode, leave that mode on for ten seconds and the light will flash again, confirming that the mode has been memorized. To cancel programming before it flashes, turn the light off for three seconds.

The beam profile has a medium sized hotspot, though the XM-L LED produces a slightly wider hotspot and corona when compared to the earlier Quarks running on XP-G LEDs as illustrated by the lower lux numbers measured. Another big difference in output also shows in beam tint, with the XM-L having a warmer color temperature in comparison. Overall beam profile is clean with no artifacts. The Quark X AA² gets some boost in output thanks to the updated LED and the electronics does a decent job at regulating output while providing good runtimes as well. Regulation is held solid throughout the entire runtime, though note that just like the CR123 version, the maximum output on Max mode only lasts for the first 5 minutes before dropping to about 70%.

The Good - Clean and compact body design. Well-designed pocket clip. Practical implementation of programmable user interface. Very bright on initial Maximum output level relative to its size. Well regulated output performance on all output levels.

The Bad - Nothing significant.

The Relative - Clean beam profile with a neutral tint. Uses a forward push button switch. Is unable to tail stand.