Body: Overall, the Quark CR123² 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. The Quarks are advertised as having square-cut threads, though they're rather fine and you probably won't notice the difference to regular threads, unlike those on the recent JETBeam's for example. 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 forward push button switch in the case of the tactical version of the Quark CR123², allowing for momentary activation. The switching mechanism has average tension and travel. It provides a positive tactile feedback when fully engaged. The rubber switch cap slightly protrudes out the rear end of the tail cap, so tail standing is not possible. 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.

Bezel/Head:The Quark series of flashlights are the initial offering by relatively new manufacturer 4Sevens. The current line of Quarks are available in either regular or tactical versions. The light reviewed here is the Quark 123² Tactical. 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..

Output:The Quark CR123² Tactical is able to provide two output modes at any one time, selected by either tightening or loosening the head. For each position, the user is able to define their desired output level. Programming output modes for either positions is done by performing a loosen/tighten motion in quick succession four times. Depending on which position you have the head after the fourth turn, that's the position which you will program for. The available output modes available are Moonlight, Low, Medium, High, Max, SOS, Strobe and Beacon which can be cycled through by clicking the switch while in programming mode.

The beam profile has a medium sized hot spot tapering smoothly towards the corona. Between the Low to High output levels, the beam has an almost perfectly white tint when compared to sunlight, but there is a slight tint shift towards the cool side when running the light on maximum output level. The Quark CR123² is advertised to output a maximum of 190 lumens, tests done with this review sample produced a peak of 219 lumens. The electronics does an excellent job at regulating output on all battery configuration supported as can be seen from the runtime graphs below, while providing good runtimes as well. Which ever battery configuration you decide to use, you can expect relatively good performance.

Runtime Plot: Runtime with a 17670,CR123 and 16340 are shown below.

Switch: The switch is a rubber covered textured clickie and is fully recessed in the tailcap which allows the light to stand on end and be used as an electric candle. Despite the fact that the switch is recessed, it is very easy to use. Click on, click off, press for momentary, twist to change output from bright to dim, and back again. The dimming system is very unique, using a piston-like ring inside the tailcap to change output.

Conclusions:The Good - Clean and compact body design. Well-designed pocket clip. Practical implementation of programmable user interface. Well regulated output performance on all supported battery types.
The Bad - Nothing significant.
The Relative - Beam has a neutral white tint, except on Max level which shifts slightly to a cooler tint. Forward push button allows for momentary activation. Is not able to tail stand..

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