The Hitchens is a top shelf sleeping bag for all season use. With its streamlined design, ultralight ripstop nylon shell and 850-fill power down stuffing, it delivers phenomenal warmth to weight.

Big Agnes has focussed its energy on delivering a high performance lightweight bag. Gone are the superfluous features. The nylon shell shaves precious grams, as does the half-length zip. A single cinch cord completes the Hitchens’ features.

As a result, it weighs a mere 770g, of which 510g is down. This is pretty revolutionary for a four-season sleeping bag that is rated to a comfort limit of -7˚C. It’s about 400g lighter than my current winter bag, which I considered to be light.

Every detail has been pored over to cut weight without compromising comfort. The bag is snug, anatomically tailored to minimise dead space, but it doesn’t feel restrictive. The hood fits tightly around the head, a baffle runs down the zip to cut airflow, and another runs over the neck. A single drawcord cinches the neck tight, leaving just your mouth and nose showing.

It could be argued the focus on reducing weight has gone too far. For a top-end sleeping bag, it would have been nice to get a dry-bag stuff sack. Instead, the Hitchens comes with a non-waterproof stuff sack made of the same lightweight nylon as the outer.

Perhaps the real test of the Hitchens’ value will be its durability. The DownTek insulation has been treated with a hydrophobic coating to reduce clumping if the bag gets wet. Hydrophobic down is becoming the norm, with new sleeping bags, but it hasn’t been around long enough to judge how it will stand the test of time in comparison with untreated down.

Though not cheap, the Hitchens offers unparalleled warmth for its weight. This makes it an ideal choice for winter trips and above-the-snowline camping or climbing where weight is a key consideration.