I just finished putting together a grow light using four LedEngin's deep red and one blue. It works like a champ. I mounted them all on one U81C and stuck it in a desk lamp so I could move it around but it is much heavier than I thought so I needed to prop it up. I attached an extra 80mm computer fan to the heatsink but I don't think it needs it because it is cool to the touch right by the LEDs after running all day. I recently checked Mouser for more of the 15W 660nm reds but, it appears they are no longer in production. I want to get some kind of enclosure going maybe underneath a sofa table or something.... I guess I'll have to figure something out with the 10W.