How it works
The parts of a sleeping bag, shown on a mummy bag with its zipper half open. The second drawing is a cut across the top of the bag, to show the filling and what holds it in place.
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Where the warm air is kept in
A mummy bag narrows from the shoulders to the footbox and has a hood for the head. Three parts stop warm air leaking out: a drawstring closes the hood round the face, a draft collar seals the neck, and a draft tube lies behind the zipper.
Inside the bag
The outer fabric is the shell. Under it is the insulation, which is down or synthetic fiber. Baffles, walls of fabric inside the bag, keep the insulation from shifting and leaving cold spots.
- The draft collar is at the neck; the draft tube runs along the zipper.
- Carry the bag in its stuff sack, but store it loose in the big storage sack.
Questions and answers
What are the parts of a sleeping bag called?
On a mummy bag: the hood with its drawstring, the draft collar at the neck, the zipper with a draft tube behind it, and the footbox. The bag itself is a shell filled with insulation, held in place by baffles.
What is a draft collar on a sleeping bag?
A tube of insulation inside the bag near the hood opening, also called a neck baffle. It sits round the neck and shoulders and keeps warm air from escaping from the body of the bag.
What is the difference between a draft collar and a draft tube?
Both are tubes of insulation. The draft collar goes round the neck, near the hood. The draft tube runs the length of the zipper and stops heat escaping through it.
What are baffles in a sleeping bag?
Pieces of fabric inside the bag that divide it into chambers. They keep the insulation in place, so it does not shift and leave cold spots.