I made a M50 Sleeping Bag last year when the bright orange was the only option.
I ended up adding just under 2 ounces of down to it to make it a sub 20 ounce bag that I could take down to 32*.
I ended up getting a full 4" of loft out of it while the bottom having 1 1/2" and the top 2 1/2".
The bag has a separate vertical area on the left top of the bag that connects to the horizontal baffled spaces. In doing this I can move down from any of the horizontal spaces into the vertical space and move it to any other horizontal space.
The hood is fitted and has the ability to take some down out of the bottom of the bag. The bottom is segmented into 3 spaces so the down can disperse a lot easier into the non compressed spaces. I also added a piece of fleece to the hood. There were a few too many seams that came together in the front of the fitted hood. the fleece makes it much better and picks up the hood off my head ever so slightly making it much more comfortable.
The zipper is a 60" #3 YKK. I have it this length so I can use it as a quilt on a warm night. The zipper was also made to fit right between my arm and body (as you can see in the picture). This way I did not need to worry about any drafts.
This bag is made to fit me and only me. There is some how no areas that have any dead air spaces, yet there is still has room for layers. Both this bag and the new sub 10 ounce top quilt I made are by far my favorite pieces of gear. I would even take my bag over a Summerlite.
