[rotorwrench]

I've been around dropping and regulating systems for a long time and all of them generate heat. Most are insulated from making contact with flammables. The flea-pay stuff doesn't look like it has any way to get rid of the heat plus it has a two wire input and a two wire output. How are you supposed to insulate your load from ground?

I would be skeptical about the longevity of those products and whether they are safe to use or not. You certainly don't want your car to catch fire due to a poorly made product. -Caveat Emptor-