The Tetra HT 100w heater is a fantastic small heater for fish tanks up to 150 litres. Part of the Tetratec range that features products with not only exceptional quality and reliability but also fantastic value for money. Features: Automatic Safety shut-off to prevent damage. Accurate temperature setting from 19?C to 31?C. Temperature steps of 0.5?C. Borosilicate 2mm thick shock-proof glass tube. On/Off light. Waterproof and fully submersible. Tropical and Marine Safe.