Here's my experience with these heaters
I ordered 2 - 300W Won Pro-Heat Titanium Heaters (Not the digital ones) from a certain online vendor. I did a little test run in my garbage can I use for water storage. The first one Shocked the PIS5 out of me!!! It also heated the water up to 90+ degrees, even set on the lowest setting. The second one also heated the water up to 90+ degrees. When I would try to turn the temp down the red light wouldn't turn off, but at least it didn't shock me!! Boy am I glad I did a Test run!!!
The Vendor replaced them without a problem. I considered replacing them with a different brand, but the vendor said that the Won Pro had the highest success rate of any heater that they sold, and they sell a lot of heaters!! So I did the test run on the two replacement heaters I got. No shocks this time!!! I tested them at different times, leaving a day in between test runs for the water to cool down a little. I set them to 78 , but the water ran 82 . This happened with both heaters. At this moment the water is that exact temp (82) , and the light is on indicating the heater is on! But it does turn off when I turn the dial down. They are not precise too +/- 1 degree as advertised on the box, but they do seem to be consistant and stable.
Jut figured I would share