HHM 4 I bought this as I wanted something that could be used by guests or in an emergency. I was a little worried because this seemed too thin when I opened it, so have been using it myself for a while. So for it has kept me warm in a very cold house (thanks to Hokkaido winters and the ridiculous lack of insulation in Japanese houses) so I'm happy for guests to use it. Not sure it would work so well outdoors in winter, wind and ground conditions will have a much bigger impact, but I could see this being good in spring/fall for outdoors. The zipper is on the left as standard I think, so as a right handed person its a bit awkward to open and close the zipper. And the zipper is CONSTANTLY snagging the material, so it can be really annoying to close it up. The inside is soft material and is very comfortable, and has a lot of room for those of us who like to move around when we sleep. I'm 180cm and 100KG, and it's plenty roomy for me.