Patented heating film and special shatterproof glass make this submersible heater virtually unbreakable. Theo switches itself off if the heater is not fully submersed - avoiding overheating and damage.  Precise temperature knob clicks in 1°F increments, and an indicator lamp lets you know when it's on. Suction-cup clamps included. 5-1/2 ft. cord. UL-Listed.