They are mounted to heat sinks individually and thermally glued to the aluminum case. It needs air flow to stay cool. It gets hot if there is no air flow. I rode with it for an hour and it worked great. I kept it on at my shop with a fan on low for 2 hours and it kept working without a problem.scar said:Those are going to burn up real quick without any heatsinking! Looks like you are just relying on the MCPCB's?