Test wrote a review of Arc'teryx Cierzo 25 Backpack - 1648cu in on July 29, 2014
Familiarity: I've used it several times
Rei Flash and Marmot compressor packs are both in this lightweight category, but IMHO the Arcteryx Cierzo 25 feels more durable and has a better compression system. Even though the Cierzo 25 sheds water well, I carry anything that needs to stay dry in a dry sack. A hydration sleeve is included when the thin foam back pad is removed from it's internal pocket. Knowing how to pack a frameless backpack will make this easier, but there's really nothing to it. What I also like is the bag's other versatility---it's ability to expand from 1300+ cubic inches to 1600+. And even though the harness straps and belt are thin it delivers serious comfort w/ lightweight gear. I went with the black bag because the straps appear to be less stressed and just as effective. The one size fits all also fits all and that's a nice factor too. Over all I've given this
pack five well-deserved stars.