Western Mountaineering

Ten degrees, six and a half inches of loft, twenty ounces of 850-fill down, and three inches more shoulder girth than the UltraLite — which is the point of it. The VersaLite is the bag for someone whose trips run from October frost to alpine summer and who would rather carry three extra ounces than own two bags. At 32 ounces it weighs less than plenty of 20-degree bags in this catalogue, and the girth means a puffy jacket can be worn inside it without crushing the loft.

Best for: One bag covering shoulder season and light winter

Western Mountaineering has been building bags in San Jose for fifty years and has never published an EN or ISO rating for any of them — the 20 °F on the UltraLite is the company's own number, and its reputation rests on that number having been accurate for two generations of backpackers. What it does publish is the physics: 5.5 inches of measured loft, 16 ounces of 850-fill goose down, 59 inches of shoulder girth and a 12-denier shell, for a total of 29 ounces. Continuous horizontal baffles let you shake the down to the top on a cold night or to the sides on a warm one, which is a feature almost nobody else offers and which more than compensates for the missing zip vent.

Best for: Buyers who plan to own one bag for twenty years

The UltraLite cut wider: same 20-degree rating, same 5.5 inches of loft, five more inches of shoulder girth and three more ounces of down to fill the extra space. Two ounces of total weight is the whole cost of the upgrade, and for anyone who has felt pinned in an UltraLite it is the obvious choice. The 7'0" length is the only bag in this catalogue that fits someone genuinely tall without compromise.

Best for: Broad-shouldered or very tall sleepers who want a proper down bag