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Sleep systems

Draft collar

Also called neck baffle, yoke

What is a draft collar?

A draft collar is an insulated tube around the neck opening of a sleeping bag, cinched to seal the gap at your shoulders. It stops warm air pumping out of the top of the bag every time you move, which is where most heat is lost.

Draft collar at a glance

Where
Around the neck, inside
Stops
Warm air pumping out as you move
Found on
Cold-weather bags

Why a sleeping bag pumps warm air out

A sleeping bag is a bellows. Every time you roll over, the bag compresses and pushes air out, and the easiest exit is the big hole your head is sticking out of. Warm air leaves, cold air is drawn in around your shoulders, and the cycle repeats all night.

What a draft collar does about it

A draft collar closes that. It's a padded tube running around the inside of the bag at shoulder height with its own drawcord, and cinching it separates the space around your body from the opening at the top. On a cold night the difference is large enough to be worth several degrees on the rating.

When you do not want one

It's a cold-weather feature and a reasonable thing to leave out of a summer bag, where you want air moving and the extra ounces are wasted. Take one as a signal: a bag with a proper draft collar, a hood that shapes to your head, and a zip baffle was designed by someone thinking about cold nights. A bag rated to 20 degrees without any of them was designed to hit a price.

What this means when you're choosing

  • Its own drawcord, separate from the hood's
  • Enough loft in the collar to seal rather than just mark the position
  • A zip draft tube as well, since the zip is the other big leak

The common mistake

Leaving it loose because it feels restrictive

An open draft collar is the same as not having one. Cinch it until it seals lightly at your shoulders, which takes some getting used to and is worth several degrees on a cold night.

Common questions

Do I need a draft collar?

Below about 30 F, it makes a noticeable difference. For summer bags it's dead weight, which is why you rarely see one on anything rated above about 40 F.

How tight should the draft collar be?

Snug enough to close the gap around your shoulders, loose enough that you don't feel it on your throat. You should be able to turn your head inside the bag without dragging the collar with you.

Where this comes up

Guides on Tom's Hiking where draft collar changes which product is right for you.

More in sleep systems

R-value

R-value measures how well a sleeping pad resists heat escaping into the ground. Higher numbers insulate better, and since 2020 every brand has tested to the same standard, so the numbers finally compare across brands.

Fill power

Fill power measures the loft of down: how many cubic inches one ounce expands to fill. Higher fill power traps more air per unit of weight, so an 850 fill bag is lighter and more compressible than a 650 fill bag of the same warmth.

Fill weight

Fill weight is how much insulation is actually inside a sleeping bag or jacket, given in grams or ounces. Paired with fill power it tells you what a bag's warmth is made of, and it's the number brands are least keen to publish.

Hydrophobic down

Hydrophobic down is down treated with a water-repellent finish so it resists moisture, dries faster and keeps some loft when damp. It delays the failure that untreated down suffers when wet, but it doesn't make down behave like synthetic.

EN/ISO temperature rating

EN/ISO is the standardised lab test that gives sleeping bags their temperature ratings. It produces several figures, and the two that matter are comfort, aimed at a standard cold sleeper, and limit, aimed at a standard warm sleeper.

Mummy bag

A mummy bag is a sleeping bag cut wide at the shoulders and narrow at the feet, with a hood that closes around your head. The taper leaves less air inside for your body to heat, which is why it is the warmest shape for its weight.

Baffle

A baffle is a fabric wall sewn between the inner and outer shells of a down bag to hold the down in place. Without baffles the down migrates to the low side and leaves cold spots where there's no insulation at all.

Footbox

The footbox is the shaped end of a sleeping bag or quilt where your feet sit. It's built with extra volume so the insulation isn't crushed flat by your toes, which is the coldest spot in most sleep systems.

Backpacking quilt

A backpacking quilt is a sleeping bag with the back removed and no hood, strapped to your sleeping pad instead. It cuts weight and bulk by deleting insulation that a bag crushes flat underneath you and that does nothing there anyway.

Pad attachment system

A pad attachment system is whatever keeps your bag or quilt joined to your sleeping pad, usually elastic straps that pass under the pad and clip to the quilt. It stops the two separating in the night on any surface that isn't flat.

Underquilt

An underquilt is an insulated quilt that hangs on the outside of a hammock, cradling it from below. Because your body never lies on it, nothing compresses the loft, which is why it works where a sleeping bag underneath you does not.

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