I'm honestly not a fan of Tetra-tec hardware in general. It seems cheaply made, not very long lived, and I had a heater cook a tank of fish once
Some people like those heaters, but I have heard a few complaints that they don't regulate heat as well as better brands of submersibles (like ebo jager, Visi therm), at least the smaller model tetra heater 'inserts'. They seem a bit pricy too, compared to a submersible...a visitherm stealth would be comparable since it's shatter proof. I didn't have luck finding a wattage on it either, but I didn't look very hard.