Ducky wrote a review of Outdoor Research DryComp Ridge Sack on May 16, 2010
Used on Grand Canyon raft trip and it stayed dry through rapids with repeated soakings. Fit is OK for very small woman. Would fit better if you are larger than 5'1" and slender. I plan to try it for bike commute too. No internal structure so if you don't have it full it is kind of floppy. But having both waist strap and chest works fine. Can't carry much weight - 10 lbs is probably the limit. Folds down small. I'm happy with it.