Hydor Theo water heaters features PTC patented thermal technology which makes it among the safest water heater lines on the market. Made from specially engineered shatterproof glass which, while not unbreakable, is designed to resist breakage in most normal situations. Theo heaters unlike its rivals will not break if the water level goes beneath the heater. • The first shatter-proof heater thanks to the peculiar glass tube. • Maximum security: THEO is shock resistant thanks to the PTC heating element and the shatterproof glass tube. • Free positioning in aquarium with supplied suction cups. • Self-limiting: the patented PTC heating system guarantees operation in complete safety because in case of dry running there is no danger for damage. • Two year manufacturers warranty.