6.8.
All Featherweights, Lightweights, Middleweights, Heavyweights and Super Heavy
Weights, must have at least one surface mounted non-filament power light that is
illuminated when power is supplied to the robot. (i.e. when the link is in.) The power light
can be any colour but must be non-flashing and be in contrast with its surroundings.

It is easy to do, they dont easily get broken and take very little weight.