The device appears to be solid and well built. It's the only unit I've found that has both a Variac AND an Isolation transformer in one unit. It's roughly half the price of buying both units separately (not to mention the reclaimed workspace). As near as I can tell, the output is indeed isolated from the input, as claimed, including the ground. I'm just a hobbyist, not an electrical engineer, so please accept my opinion in that that context.