The Radiator is an energy-based weapon that can be used by Humans and Androids. It is built by using a Powered Accelerator with a Fuel Cell. It is a short range weapon, and hence is best used against melee aliens. Not recommended for use by Androids due to the significant energy cost. It is quite effective against laser turrets, if you can get close enough to use it.
The Radiator is more widespread, and hence easier to use than a Laser pistol at point blank range, but the Laser pistol is generally more cost-effective, and the range of a laser pistol makes it generally the superior choice.
The parts needed for making it can also be used to make a Pistol, using a Pistol Chassis with the Powered Accelerator instead of a Fuel Cell. It is recommended for Androids to do this, since the Pistol Chassis is easily found right outside the Marine Hermit's hut, and it doesn't use any energy.