Bought to protect my $100+ backpack as a check-in baggage in airports, planes, tranes, buses, etc.

Almost perfect! I've made one important addition to the handle (velcro wrap) in the very beginning before my first use to keep both handles together and avoid trapping in the moving conveyor belts and carousels. It is so rare today to see such an inexpensive, simple and optimal user friendly design & construction for transportation and outdoor purposes. When bag is fully unzipped to the bottom it lays flat on the floor, no need to push things into, just put a backpack on and other stuff and zip from both sides - done. See my step-by-step images for the purple bag (my camera showed it blue).

When empty compacts to a book size (see my posted photo with DVD, book and phone for comparison) and weighs a pound or little more. Insert it in your backpack and hike to backcountry. Almost 5-star product and hats off to the designers (except missed velcro).