AP Products 013-665 2" x 25' Flex Air Duct

This is what arrived. Couple items for scale. Basically the worlds smallest aluminum dryer vent duct. Feels very solid. Super stoked to install on my diesel heater. I have the kind that has four 42mm output ports. Took only a couple days to arrive, to St. Louis area, much faster than Amazon estimated. There is an inner lining, which I believe is polyester. Not 100% sure on this part, but typically if there is a plastic lining in an air ducting, it is usually polyester instead of vinyl or something else because polyester is better at high temperatures. The inner liner is thin, smooth and makes crackling noises when moved like other polyester duct linings I have worked with, and not soft/more malleable like vinyl. So it should work very well connected to a heater.