Just to let you know the fins on the head really do nothing as in the head is the optic cavity which produces almost no heat and even then the optics cavity is a good 1.5cm away from the outer wall so you can think of those pretty heat sink looking fins as just a protective barrier for the optics the real heat is right above the button where the diode is located at.... it really just relies on that chunk of aluminum to keep it cool that is why the duty cycle is 5min on to 3min off to allow that chunk of aluminum to cool down .... The fins may help a little but not nearly as much if the thing was actually made solid
Well, as aluminium is a good conductor of heat, it doesnt matter -that- much where the fins are. By the looks of it this thing has enough surface area to dissipate the pump heat to its surroundings with or without the fins, though they will help a bit.
Its basically a rod 22 cm long a 4cm diameter, which make a pretty decent heatsink for the 2-3 watts it needs to get rid off. It should not heat up more than a few degrees over ambient if left running continously. It is just as large as a laserglow Aries series, and those run 100% duty cycle - at least at the 250 mW level.