Please note that this review is based on a test sample of the Quark X 123². Right up the front is a smooth bezel. A sapphire-coated impact-resistant glass lens sits slightly recessed within the bezel. Behind the lens is a medium-textured which has a very well-polished surface finish with no flaws or blemished to be found. The LED sits perfectly aligned at the bottom of the reflector cup. Looking in from the rear, the battery contact points on the PCB can be seen. There is a physical reverse polarity protection design implemented by means of two raised crescent-shaped surfaces. The exterior of the head has a plain cylindrical shape with no unnecessary aesthetic machining. A large area of its surface is covered by a band of diamond-textured knurling which provides good grip and allows for easy twists of the head.

Overall, the Quark X 123² feels compact for a light which runs on 2x CR123. Keeping with the same clean cylindrical design concept, the battery tube is almost totally covered in knurling on its exterior apart from three flat faces. The entire light is coated in black Type 3 anodizing which is consistent throughout. There is also a removable clip which comes pre-attached to the battery tube. It's held securely in place by a retaining ring which threads into the battery tube from the rear, and the clip also sits in a small notch which prevents it from sliding around. The interior diameter of the battery tube accommodates most of the supported battery types easily accept for protected 17670 cells which can be a snug fit. The threads on either end of the battery tube are well cut and mate nicely with those on the head and tail cap. Unlike the earlier Quarks though, the X 123² doesn't have square cut threads. There are also rubber o-rings placed behind the threads for water resistance. The threads on the battery tube are of the same size on either side which allows the user to swap the head and tail cap positions, thus allowing the clip to be orientated for either head-up or head-down carry. The clip is stiff and provides a secure hold. The tail cap houses a reverse push button switch. The switching mechanism has average tension and travel. It provides a positive tactile feedback when fully engaged. The rubber switch cap sits recessed within the tail cap so tail standing isn't an issue. There are holes machined into the tail cap for lanyard attachments as well. The rubber hand grip attachment allows the light to be held while allowing your fingers to be free for use.

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

The Quark X 123² has output modes separated into two sets. With the head tightened, half-presses of the switch cycles through Maximum and Strobe. With the head loosened, it cycles though Moonlight, Low, Medium, High, S.O.S. and Beacon modes.

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. Overall beam profile is clean with no artifacts. The Quark X 123² gets a boost in output thanks to the updated LED and the electronics does a decent job at regulating output while providing good runtimes as well. Do note that the electronics steps down output after about 5 minutes when Maximum output mode is selected. This was probably intended as a safety feature due to the amount of heat produced by the LED and the relatively small size of the flashlight's body which limits its ability to dissipate heat. After peaking at 446 lumens, the Maximum output level then settles to about 312 lumens for most of the remaining runtime. This amount of light is very impressive coming from such a small package.

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 slightly warm tint. Uses a reverse push button switch. Is able to tail stand.