Insulated with 850 fill goose down, the Spark SPI is a summer and fair weather bag that's comfortable down to 54°F — though you can lower that by dressing warmer. The Spark SPI might not be a replacement for an intense camping bag, but this it awesome for anyone who's doing anything from cycle touring to crashing on a friend's couch. Seriously, this thing is so small that Sea to Summit had to engineer a new compression sack.
Ethan Wolff-Mann is the Gear editor for Supercompressor. A Vermont native, he loves biking, running, rock and roll, and words. He never believed a word Lance said. Hear him testify on Twitter @ewolffmann.