4 years late, but I got an answer for you: In-built cooling and a vibration dampening layer. Their helmets, by the end of their career, were actually extremely sophisticated and had a lot of neat features beyond just lighting options. They had ventilation, sound deadening, *and* a small internal display that helped them keep time with the current track, the current track, the *next* track (so they could come up with seamless transitions easier), and an in-built mic so they could communicate with each other without having to take their helmets off.
Love this. RAM Was an amazing album for sure, but most of the songs are laid back and chill. Can't imagine what the experience was like to have this final song slam the dance floor. The release of energy must have been amazing.
