It's 84 degrees so the test hang was very short. I just took a 0*Alps bag and cut a hole in the foot end and taped it up since I don't sew. Kinda crude but it sure is hot in there. Only problem I had was getting the bag zipped up once I was in there. I think the answer is attach the left side of the bag to the hammock (WBBB) with velcro or something like that. I can only imagine how warm it will be in the winter but I bet it will go into the single digits and maybe below. Bag is synthetic fluffy stuff and the loft is about 3". Icouldn't tell if there was any compression of the bag while I was inside but Idon't think there was since I couldn't feel the bag very well when it was zipped. The plan is to have a breathing hole at the head to deal with condensation.