My first insulated hammock was to have down insulation in 6" tubes (battens running the length of the hammock. When I first tried it out, before filling the tubes with down, I found that the top surface stretched so much that there wasn't enough space between the top and the bottom surfaces for the down to loft. I cut 6" wide strips of reflectix and put them into the tubes as a temporary fix. The resulting hammock was so comfortable and warm that I used it for an entire year before I finally took it apart and added bigger baffles so I could use the down. Because the individual strips of reflectix could slide independently, they conformed to the shape of the hammock extremely well. The only drawback of this arrangement was that it didn't compress, so it made a pretty big roll tied onto the top of my pack.