High Quality, Break Resistant Glass Construction Fully Submersible Simple Installation Available In A Variety Of Sizes Suction Cups For Securing To The Aquarium Visible Temperature Setting For Use In Fresh And Saltwater. Two suction-cup clamps included. 5-1/2 ft. cord. Safety Precautions #1Unplug all electrical appliances before making water changes or performing any maintenance. #2Use this heater indoors only. #3Check voltage to verify the one that's reported on the heater label corresponds to your electrical supply. #4Do no use if either the cable or the heater are damaged. #5Do not plug in when out of the water. #6Keep water at or above "Minimum Water Level" line. #7Fully submersible, but we recommend keeping top knob out of the water.