I was worried about this because not only does the aluminium body of the lamps basically look like huge heatsinks but also because I was mounting them quite close to the headers.It was one of the warmest nights we've had recently when I tested them, and I was switching them on and off for around an hour and they were cool as anything when I checked afterwards, I didn't detect any heat whatsoever. That's impressive indeed.I think there must be a time when they do get hot but I reckon the conditions have got to be pretty extreme.