Heavy duty waterproof tarpaulin trunk bag with expanding main compartment and fold down sized that increase carrying capacity from 9L (550 c.i.) to 36L (2197 c.i.). Customer requested additions such as adjustable dividers ice pack compartment and elastic cords for taking extra layers for unpredictable weather. Mesh helmet holder on the exterior keeps your helmet safe and secure during stops for provisions. Drawstring closure water bottle holder