COB And CREE - Welcome To The World Of LEDs | A Guide To Our Lights - See.Sense
LED test / review - New Cree XLamp XM-L2 U3 color kit 51 (≈ 6200 K, design change after PCN issued) - Flashlight Modding and DIY Parts - BudgetLightForum.com
How to distinguish LEDs CREE XM-L T6, XM-L2 U2 and XP-E Q5 visually (external differences) - YouTube