Dual molded side panels combine with flexible 600 denier fabric to form a semi rigid weather resistant Topeak Trunk Bag DXP. A divided main compartment and side panels expand for extra storage capacity and the rear water bottle holder lets you carry more water on extended trips. This version attaches with integrated straps. Pannier deployment requires a beam rack with side frames attached or a traditional rack with struts to prevent panniers from contacting rear wheel.