Using "freshwater only" heater?

[kurbanas]

I have just bought and am using this Hygger heater. But apparently it is only for freshwater, something I didn't even think to check when I was shopping for heaters. I assumed (maybe naively) that all heaters could be used in either.

But I don't understand what could be "freshwater only" about a heater and am trying to figure that out, and am coming up empty. An answered question on the amazon listing says "the composition inside will deteriorate," which is not a satisfying answer to me.

Has anyone encountered this or have any experience with a "freshwater only" heater?

 

[elysics]

Probably cheap screws and stuff instead of titanium. Who knows maybe there's a bare metal conductivity probe in there to check whether it is underwater

 

[bushdoc]

Not a very popular brand, not cheap either. There are more reliable and tested brands for saltwater tanks. If you have expensive setup with expensive fish, corals, inverts, I would go for something like Eheim brand.