Difference between all the color temperatures / Kelvin ratings;The K (kelvin) rating specifies the color temperature of a light source. The K ratings in HID xenon bulbs go from an almost yellow 3000K to an 8000K which is a more blue color (there are even higher K rating bulbs). Generally speaking (the color perception is a bit subjective) the K ratings and colors are as follows; 3000k = Almost yellow4300k = White with a hint of yellow (best for driving in bad weather conditions and comfortable for the eyes)5000/5500k = More pure white color, good for general driving conditions and a modern color6000/6500k = White with a hint of blue8000k = bluer than the 6500k When light output/visibility is most important we advise the 4300k color temperature. For a modern look and a good output/visibility, we advise a bulb in the 5000/5500 range. And the customers searching for an icy white with a bit of blue color, the 6000/6500 is the best option. The K rating of the xenon bulbs doesn't correlate with the light output, so a higher K rating won't give a higher light output, it only tells the color of the light. In the picture below you can see the difference between all the color temperatures: