Topeak MTS Strap Mount TrunkBag DXP features dual molded side panels combine with flexible 600 denier fabric to form a semi rigid weather resistant trunkbag. Divided main compartment and side panels expand for extra storage capacity. Rear water bottle holder lets you carry more water on extended trips. 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.