Fluval M Series heaters combine modern aesthetics with reliable Italian construction. Employing an ultra-slim profile, M heaters are a welcomed departure from traditional, more bulky designs. The M series is highlighted by its reflective borosilicate glass tube, which allows it to blend in seamlessly with its aquatic surroundings. Within the tube itself you’ll find a computer-calibrated thermostat, which undergoes a 16-point quality assurance program for superior temperature precision.