This state of the art heater features an easy to adjust temperature control knob, double temperature reading and double power indicator lights. A completely submersible design with a water tight seal allows you to mount the heater vertically or horizontally. Features 500 micron silver contact, specially designed thermal diffusion heating system and a 2 mm thick Borosilicate tube for unequaled life. Rena Cal Excel is CSA tested and approved for safety and performance.