AFAIK, no resistors. I am trying to remember off the top of my head, but I think the voltage drop was 5.76 something volts across the head (all 5 LEDs) and over 260 mA = over 52 mA per LED. Pretty badly overdriven. Half-life of the LEDs would be expected to be 2000 to 4000 hours at this rate of current draw.