Aquael Heater Comfort Zone Fix 25W precision of operation (± 0.5° C) compact size = ease of installation fully automatic operation dark colour: the heater will be inconspicuous Length: 163mm The new COMFORTZONE FIX heaters are fully automatic devices that maintain constant water temperature at 25°C (± 0.5°C). The heater is very simple to operate: just place it into the tank and connect it to the mains. The device turns on and off automatically the duration and frequency of its operation depending on the temperature conditions prevailing in the tank. Another advantage is their relatively small size compared to regular glass heaters: just 163 mm (25W and 50W models) 185 mm (75W model) or 205 mm (100W model). Thanks to their size the heaters can be easily installed in smaller tanks.