The Interchange Waterproof Rear Trunk keeps all your gear dry in inclement weather with its waterproof roll-top closure. This great pack attaches to and removes from Trek's Interchange Racks (sold separately) in seconds and installs to most other racks with Velcro straps. Plus, it boasts 750 to 1,000 cubic inches of expandable storage space to carry ride essentials or the makings of a great picnic. And, the Interchange's aerodynamic shape fits nicely and looks great.