All I can tell is that Iv'e got three of them running with no problems at all. Pretty dam accurate as well. That being said, I don't think they would be my first choice. I picked them up new at a closing, three for thirty dollars about a year ago.
they come with warrenties too i think, but, i have to addmit my jager does it better, saves power too! compared to aquaones... i needed a 200watt for my 4 foot (aquaone) jager... 150watt
I just bought a couple 300 w Visi Therm heaters at drfostersmith.com for only $22 each. I've had lots of different kinds of heaters but these are my favorite (since one of my Stealth's quit working and another one developed fat bubbles in it all around.
They are kinda junky IMO. I'd go with the jagers. Well worth the extra cash if you value your fish. I have some expensive plecos that is why I try to use the best.