Ortlieb Back Roller City is, like all other Ortlieb panniers, completely waterproof. Closing the pannier is simple: roll the mouth a couple of times and insert the buckles on their counterparts on the sides of the pannier. The package contains two panniers. - QL1 system: two adjustable upper hooks and one lower hook, requires Allen key for adjustment - Large, high quality 3M reflectors on both the front and back - Welded seams - 5 year guarantee against manufacturing defects - Comes with adapters for different width handlebars - Simple hooks that attach to the rack are opened easily by pulling the handle - Easy to clean, both inside and outside Volume and weight refer to a pair of panniers. The package contains two panniers, one for both sides of the bike.