Topeak aero wedge pack dx the aerodynamic wedge shape lets these under seat bags slip easily through the wind while the internal pockets keep tools away from inner tubes and other delicate items the dx small is the perfect size for a road tube and essential tools for roadies where as the dx medium provides just the right amount of room for an mtb tube patch kit and a tool for mountain bike use features 3m reflective strip redlite clip bag attachment qr wseatpost strap f11 capacity 045