Fireflies use chemistry to emit light.
Low output red ones in taillights may not get hot,
but the white ones that light up a fair bit of the highway in the dark
are using heat sinks to draw off excess heat to make that bright light reliable.
in the case of my E Delux the aluminum case is directly connected to the
diode heat sink mount, and so part of the heat dissipation.
Last edited by fietsbob; 02-20-13 at 12:29 AM.