this large bag snaps right onto the back rack. It fits on either side, or if you had two you could carry a weeks worth of groceries. A net on the outside carries a bottle of water. Much easier than a backpack, never notice it while riding.
Like the quality of the bags. Easy to install and remove the bags on and off the bike but needed a little help figuring out how to snap the bags shut. My recommendation is send a small pic along with the bag on how to close them but that's it. Love them and find them super useful.
Having the Pannier Bag is perfect to store items in while riding. The only downside is the bag hangs a little lower off the rack and to secure it with the velcro strip, it needs to be more forward. it's a good purchase and we like it alot.