Ordered a section of Z-Flex double wall pipe for my natural gas unit heater in my garage. GadgetsGo had this pipe at the most cost effective price I could find online without having a contractor account. I would definitely shop with GadgetsGo in the future.
Advantages: Very fast shipping once released to the manufacturer.
Disadvantages: The only disadvantage was that it took a couple days for my tracking number to post on the website however this most likely stems from logistics impacts due to Covid.