Sea to Summit eVent Compression Sack
This is the one to buy, and the reason is the base. The eVent panel lets air out while keeping water from getting in, so compressing it is easy rather than a wrestling match, and the contents stay dry in a wet pack.
Why an ordinary compression sack is frustrating. It is a sealed bag. Pulling the straps compresses the air along with the contents, pressure builds, and the last third of the travel fights back. People give up early and conclude compression sacks do not work well. The air-permeable base removes that entirely.
Still in production, which makes this among the more useful reviews on this site. The line has been revised and the fabric names have changed, but the design is the same idea.
Best uses:
- A down sleeping bag, which is where the volume saving is largest and where keeping it dry matters most.
- Bulky clothing, especially a down jacket and a fleece, which compress far more than they look like they should.
- Dirty laundry, unglamorously, because it contains the smell as well as the volume.
What not to do with it: store the bag in it. Down needs to live lofted, and months compressed permanently reduces the fill power you paid for. The sack is for carrying.
One practical note: the waterproof base is not a dry bag. Water will find the lid seam if the sack is submerged, so for river crossings or boats use an actual roll-top dry bag.
Part of the guide to packing and organisation.