They claim to be unbreakable and you know what I don't see that happening under normal circumstances even if you get a bit rough with them. There's no Glass so nothing to crack when they over heat, not that they can overheat anyway. This device is equipped with a safety thermal switch that stops operation if it's out of water.
Modern plastic heater with termoregulation.
Wide range of precise regulation
Fully submersible (IP68 Standard)
Overheating switch control
Easy to install and service