Very clearly the manufacturer of this item has serious, serious quality control issues. The unit I received worked as it should for about 10 days - may have been less as I did not check it very day. Then it failed open circuit. I chose to use this unit with an inline thermostat to save electricity so that should have also reduced the stress on the unit. I've had mineral insulated heating elements technically similar to this last many years without fail. It's annoying enough to receive faulty products but having this thing fail is infuriating as I now have to drain all the coolant from the engine to which it was fitted and add that back once installation is complete.I have asked Amazon to supply a replacement unit in the hope that will be OK. I'll update this review with results.