In our lamps, we are using highest efficiency LEDs and a driver circuit we carefully optimized for lowest possible losses. Still, the high power output of our lamps heat up the case. For most activities like caving or running, this is not a problem, as even a little air movement is sufficient to cool the lamp head. In some circumstances however, there is not enough cooling, causing the lamp to run too hot. There is no damage from that, an internal temperature sensor prevents the lamp head from overheating. If you have an activity like cave photography in Indonesia, where it is warm and you have little or no movement, you can improve cooling using the add-on heatsink. This is a precision CNC machined part which fits on the back side of the caving head. You can order the lamp head with this option or do the upgrade yourself - if you have a newer lamp head with the four mounting threads.
Note that the heat sink is currently not compatible with the outdoor and orienteering head strap.