Expanse Sleeping Bag

The Expanse Sleeping Bag is a hoodless ultralight down sleeping bag with interior cinch cords that adjust internal volume without compressing the down. It is cut with a mild, roomy taper: 30 inches across the shoulders, 27.5 inches at the knee, and a footbox with a 13.5 inch minimum inside width.

900 fill power ExpeDRY Muscovy down. 10D nylon with a DWR treatment inside and out. Comfort rated at 0F, 15F, and 30F, in Regular and Long.

It is built for people who sleep badly in a narrow mummy bag and don’t want to deal with the pad straps of a top quilt.

Does a roomier sleeping bag make you colder?

Extra space inside a sleeping bag is extra air your body has to heat, and air you are heating but not touching is called dead air space. It does not insulate you, it just costs you calories and time to warm. A bag cut wide gives you room to move, but can also cause you to feel colder with the extra space your body heat has to keep warm.

That is the tradeoff the Expanse was built to break. Make it roomy for comfort, then give the sleeper a way to remove the space they are not using when the temperature drops.

How the interior cinch cords work

Inside the bag are elastic drawcords set in adjustment zones: two in Regular, three in Long. Cinch one down and it reduces the internal volume of that zone, so there is less air for your body to heat. Leave them loose and the bag returns to its full roomy shape.