The Kroma is the first surefire model to offer multiple led colors in the same flashlight (the A2 aviator combined leds with an incadescent lamp).
The Kroma has a principal 3w luxeon white led and surrounding that led it has sixteen 5mm leds, 8 of them blue and 8 of them red. The flashlight is powered by 2 C123 lithium cells.
Both the 5mm leds and the central white led have dual output levels (low and high), the color leds are selected by a selection ring near the bezel as in the U2 while the main led is acitvated o deactivated using the tailcap switch. In total you can get the following combinations:
Low red, High red, Low blue, High Blue, Low white, High White, Low red + High white, High red + High White, Low Blue + High White, High Blue + High White. Combining blue or red with the white central led produces white hotspot with a blue or red corona. We are not sure about a scenario where this could be useful. At maximum level with the high white on the Kroma runs for 1.5 hours while on the red or blue low level it can run for about 80 hours.
The red leds are good to preserve night vision, white on low is good for map reading since red marks in a map won't be visible using a red led, blue is good for blood tracing and other specific tasks,blue generates a lot of contrasts so it's nice to search for fallen items to the floor, blue is generally not very good for the eyes so in my personal taste a green/red combo would have been a lot better than red/blue because green is very helpful to attract attention due to its high visibility. The maximum white level is about 50 lumen not as bright as many other 3watt flashlights in the market and certainly not enough for tactical purposes.
The Kroma features a TIR lens as in the E1L to tighten the focus of the central led, at close range this means the beam will be square and not a circle. The TIR system makes the led able to throw the beam at further objects but it sacrifices sidespill. This is not a big problem since for close tasks or ambien illumination you can fall back on the 5mm LEDs.
As usual in Surefires the construction in HA-III aluminium is excellent, the lens and body will resist hits and impacts without breaking, o-rings make the light waterproof.
The Kroma is certainly a very cool light but it has some drawbacks, it is expensive and for most users you will not need all the modes and you may not need one set of leds at all. The total brightness is subpar for a modern flashlight so I would say that it is good as long as you have a practical use for many of the modes it has.
The Kroma retails for $300 you can read more in Surefire's website. You can order it form OpticsHQ.