These extension cords appear to be very well made. I will review them around this time each year until they fail.
I have given them a 5/5, but I have only had them for a few weeks. So far, so good. I use them in my shop which has a concrete floor covered in forge scale and frequently starts the day below 20°F. They remain flexible in these cold temps and appatently unharmed by the abrasive nature of the shop floor. I handled them when it was -2°F in the shop and they were still flexible, and after cleaning them up with a rag I can find no damage to them. They look brand new.
I also had opportunity to use them during a recent snowstorm with my new generator. I didnt have time before it snowed to install an interlock device and so I had to use extension cords. They worked just fine in the snow at well below freezing for the ~24 hours I had them out there.
None of this would be untrue of many much cheaper cords when brand new.
I look forward to seeing how these perform over time.