Topeak MTX Trunkbag DXP
This bag is designed to sit on the top of a rear bicycle rack. It is made of 600 Denier polyester with rigid molded side panels. It is expandable with divided main compartment and expandable top and two side expandable panniers. It also has a water bottle holder, shoulder strap, carry handle, 3M reflective strip, blinkie clip, and elastic top bungees. Capacity is 20.2 liters.