HPC Series Overview 2mm Quartz Glass with High Temp Resistant Guard Out of Water Sensor Protection Out of tank Control Pad Temperature Saving Memory Protection Temperature Steady Low Variance Technology The HPC heater series is a glass heater that uses an advanced digital processor that monitors and controls the water temperature in your aquarium. The heating controller receives temperature data from the remote sensor in the aquarium. The remote sensor contains no bi-metallic contacts to arc, corrode or wear out. This allows HPC heaters to have precise control, keeping the water temperature stable while avoiding wide temperature swings common with low-quality aquarium heaters. The built in display lets users know the current temperature, allowing you to easily make temperature adjustments with the control button positioned on the power cord. The remote sensor also functions as an automatic power cut-off switch. If the water level drops too low and exposes the temperature sensor to the air, power to the heater is turned off. This prevents over-heating of the aquarium, saving your prized aquarium life from harm. The HPC series 2mm thick quartz glass also features a protective heater guard to prevent aquatic live from accidentally coming in contact with the heating tube. Maintenance: Clean and confirm the out-of-water sensor is functioning properly every 30 days. Do not use heater if the out-of-water sensor is inoperative.  Refer to the instruction manual for proper maintenance and care.