More than a pound lighter than some of the other bags, and about half the size when stuffed, the REI Flash wins as the most packable bag in the test, thanks to the use of blend of down and synthetic. The bag also scores points for comfort, though it is a bit snugger than some of its competitors.

Compressibility
The Flash packs into a slim 7×15 stuff sack, and can be pressed down to about 7×10 with some compression straps or strategic placement in a pack (i.e. pressed down by a tent, for instance). One unfurled from its stuff sack, though, the Flash fluffs nicely to full loft in mere minutes. Despite extensive use and a couple washings, it never lost that loft.

Warmth to weight
While definitely the lightest in the class, it’s far from the warmest. The 41º-comfort rating is spot on – none of us really enjoyed sleeping in the Flash once the thermometer dipped into the 30s.

Comfort
When the nights stayed above 40ºF, though, the Flash was a comfortable bed. We all agreed that the cut, while slim and tapered, wasn’t constrictive provided we had properly sized the bags. For myself, that means slipping into a Long rather than Regular. Though I could fit into a regular, I was right up against the maximum length. The long gave me the wiggle room I need – both in length, so my feet weren’t jammed up an in girth, so I could turn over in my sleep without strangling.

Durability
Repeated washings after heavy use failed to dampen the loft – the down top panel stayed full and fluffy and the Primaloft bottom and sides stays thick and airy. The zipper proved secure on its run thanks to an effective backing material that eliminated catching and snags, and the ripstop polyester shell resisted all opportunities to be snagged or torn, even when being tossed around an Escalante canyon camp.

EN Comfort limit = 41ºF / 5ºC
EN Lower Limit = 32ºF / 0ºC