Symtec Heat Demon Harley Davidson Grip Warmer Kit (Left) (Chrome) Heat Demon Internal Grip Heaters are the industry leader in grip heaters to keep your hands warm. Heat Demon Internal Grip Heaters provide the best style, performance and safety to make cold weather riding a pleasant experience. No more fumbling and taking your eyes off the road to adjust grip temperature. Symtec's kits were designed to look professional when installed and provide a convenient way to set the precise grip temperature without being distracted while riding. The controller is a state-of-the-art, closed-loop microprocessor temperature control system.