Fluval E Aquarium Heater With easy to use adjustment lever the temperature can be precisely set in 0.5° increment. The integrated fish guard offers advanced protection. Fish and invertebrates cannot come into direct contact with the heater core. The glass sleeve is also protected against shocks from large fish speciesSecure slim profile mounting bracket. The heater can be adjusted or removed without removing the mounting bracket. During normal operation the temperature readout will change color if the aquarium water varies +/-1 °C or +/-2 °F or more from the pre-set temperature. Simply the most technologically advanced heaters available today, the Fluval E series advanced electronic aquarium heater with VueTech technology delivers peace of mind by continuously displaying real time water temperature. Equipped with an advanced digital microprocessor monitoring system with dual temperature sensors, the E series continuously monitors and displays aquarium water temperature, ensuring the well-being of your aquarium inhabitants. The volumes indicated are approximate values corresponding to water temperatures up to 26°C / 78°F with a room temperature of 20°C / 68°F Please refer to the size chart below, to choose your required heater size.