The Spark SL6 is available in two variations, 800CW (800 lumen, cool white) and 740NW (740 lumen neutral white). The model reviewed here will be the 800CW. The head is pretty long and quite busy in terms of design. Up the front is a crenellated bezel which is removable allowing the user to swap out the default clear glass lens with a diffuser lens which is included. The bezel is very narrow which may make it difficult to unscrew if you don't have a good grip on it. Behind the glass lens is a fine-textured aluminum reflector with the LED sitting well-centered at the bottom. Finish on the reflector is consistent and nicely polished. On the exterior the head has lots of cooling fines machined on which really helps considering the high output the SL6 is capable of relative to its size. The SL6 has a dual switch design which allows the user to choose between using the side or tail switches. Note that unlike the Klarus lights, both these switches have the same function. The switch on the head sits slightly recessed but is still easily activated due to its relatively large size. Both the switches share the same digital-style mechanism which has really short travel and a muted clicking feel. This also means that momentary activation is not possible.

The battery tube has a pentagonal design with five flat faces machines on and some ridges which help with grip. The SL6 also comes with a removable pocket clip which allows for head down carry, note that it is not reversible. There is an additional metal sleeve lining inside the battery tube which isolates the electrical path from the main battery tube itself. This tube will not accidentally slide out during normal use as it's only removable via the head end. The tail cap houses the second tail end switch. The tail cap has a crenellated lip and the switch sits recessed which allows the SL6 to tail stand without problems. There's also a hole for lanyard attachments. Slightly unscrewing the tail cap allows the rear switch to be effectively locked-out, but this probably doesn't really make any difference since there's the other front side switch as well. The entire light is finished in a gray Type 3 anodizing which is smooth and consistent throughout.

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

The Spark SL6 is capable of 5 output modes in total, inclusive of a temporary "Super" mode. Cycling of output levels is done by holding down either of the switches for about a second. The last output level is memorized even after the light is switched off. Note that holding down the switch to change output level will always start the cycling from the "Min" output level (this is different from the ST6). The sequence of output levels are as follows:

Off > Min > Med1 > Med2 > Max

The "Super" output level is activated by a double tap on either of the switches. I noticed that the double tap has to be at a certain interval, pressing it to quickly ends up switching the light off. Also note that the "Super" level will only run continuously for 5 minutes to protect the light from the excessive amount of heat radiate and will step down to the Max output level. Beam profile is nice and clean with an intense narrow hotspot fading gradually into the corona, and further on into the spill beam. The bright corona area is rather wide which accounts to the relatively modest spot reading relative to the overall lumen output. As denoted by the model name, the beam has a slightly cool white tint. As can be seen from the graph below, the runtime and regulation performance is impressive. Although, the runtime at lower output such as the Med1 seems to be rather short.

The Good - Solid regulation and runtime performance. Clean fit and finish.

The Bad - Mirrored dual switch design could have been better implemented for usability.

The Relative - Clean beam profile with slightly cool white tint. Digital push button doesn't allow for momentary activation. Is able to tail stand.