I'm not sure K2 TFFC's are out again since they were recalled. Arc used K2 TFFC in the Arc6 but is currently using P4's due to lack of availability. IMO, the K2 TFFC's are Lumiled's real answer to the onslaught of high brightness bins from Cree and Seoul. They are great in real high power lights, but if you're going to drive a LED to moderate levels, then it levels the playing field. My Arc6 with the K2 tffc has the best tint of any LED light I've ever had.