XLamp® MK-R LEDs Cree LED XLamp MK-R LEDs are built on the SC³ Technology™ LED platform and delivers up to 200 lumens-per-watt. These LEDs are available in EasyWhite color temperatures and provide the best color consistency for designs that use only one LED. The XLamp MK-R LEDs enable manufacturers to use fewer LEDs while still maintaining light output and quality that translates to lower system costs. These LEDs are now available in 6V and 12V options.