Erich Knaak wrote a review of Sea To Summit eVent Compression Dry Sack on July 30, 2010
I use one of these for my 15 degree Marmot Helium and 0 degree Mont Belle sleeping bags - not at the same time. There's plenty of room for an extra base layer and some dry socks along with the bag. I really like the eVent Dry Sacks for the ability to push all the air out and save space. If you're thinking about it you probably need it.