I just saw a video that suggested a thin foam pad over your air mattress in winter. I think it was a youtube video from Sweden. Does anyone know if there is a 5 or 6 foot thin foam pad avaialble in the U.S.? We used to use "Ensolite." I think. It was a closed cell foam that was medium density.

I used to have an ensolite pad long ago. It deteriorated after 6 or 7 years. I now own a couple of 'blue foam' pads that I lay over our double air mattress (which is otherwise uninsulated) on cooler nights in summer and the shoulder seasons. My understanding is that the blue foam adds just under 1.0 of R-value. That's something, but not a lot. I don't know what the R-value of an ensolite pad was but I haven't seen one in decades and have no idea where you could find one.

Gossamer Gear sells a thin lightweight pad:

https://www.gossamergear.com/collections/accessories/products/thinlight-foam-pad


*edit: Also MLD:

https://mountainlaureldesigns.com/product/goodnight-eva-1-8-foam-pad/

+1 on the thinlight pad. They can also help underneath a pad to keep things from sliding and to protect the pad just a little bit from punctures. And still add a little warmth.

The 3/8" plain ccf pads are harder to find these days.
MEC still has them in 1cm and 1.5cm thickness. Not cheap.

https://www.mec.ca/en/product/5041-524/evazote-standard-long-sleeping-pad

Another option, in various thicknesses:
https://www.foambymail.com/product/cross-linked-polyethylene-foam-2lb.html

I've never seen the foambymail link. 2#/cu ft works out to a 1/2 pound for a 24"x72"x1/4" mat (cutting a 48"x72" mat in half). Seems a bit heavy for backpacking.

The Gossamer Gear Thinlite 1/8" pad seems to be the same 2#/cu ft weight (but of course, thinner). I suppose it would depend on whether you just wanted to add a little insulation, or wanted a backup in case the inflatable pad failed. If the latter, 3/8" would be the bare minimum. My opinion only, based on limited winter backpacking experience. But I did sleep on the snow at 0°F on a 3/8" ccf pad, and I immediately bought a thicker one when I got home.

yup you are absolutely right! I think I got confused in my ounces to pounds conversion happening in my head... I was thinking, "16 ounces seems awful heavy for a thin pad like this".... well it would weigh 8 ounces... not 16