Sleeping bags

The limit rating means a survived but uncomfortable night, the extreme rating is the hypothermia threshold and is not used for selection at all. Add a few degrees of reserve, because a tired and hungry body generates less heat. Insulation dictates the warmth-to-weight ratio: down is lighter and packs smaller, synthetic insulation keeps you warm even when damp and costs less. And do not forget a sleeping mat — the sleeping bag does not provide warmth from below, that is where the mat insulates.